If by CRM you mean "Customer Relations Management" then here are some of the issues you will face.
* Literally dozens of solutions already exist that can be obtained commercially. Therefore you will find prices for every budget and you will find packages with many features. It will take you a long time to evaluate the packages even just to reduce the list of candidates. Then it will take you longer to more closely evaluate the best of those packages. You won't get this up right away because there will be a lead-time in choosing the package that is right for you. See also below for a discussion of the pitfalls of using such packages.
* To "roll your own" is possible, but you need to determine actual requirements. Otherwise NOBODY will be able to tell you estimates on anything about how much and long it will take to build this package. But then again, to make an intelligent choice in terms of buying vs. building, you STILL need those requirements in order to build a "best fit" evaluation matrix.
* The resources required by your company to put up one of these things will include the decisions associated with long-term maintenance. Trust me, the vendors will by HAPPY to sell you their product, but they won't maintain it for you without a VERY expensive service contract.
In essence, no matter whether you buy a Commercial Off-The-Shelf (COTS) package or you do a home-grown (HG) package, you are looking at a full-time person with a decent workstation. Add to that a full copy of MS Office that includes Access if you take the HG route. This person will be your full-time developer, maintainer, chief cook and bottle washer, whatever it takes to keep the package happy.
At the last place I worked before I retired, we had a COTS package that took two persons full-time for support, but it could handle way more than 40 people. It managed a group of 80 users in a call center that took contacts on the average of a new call every 75 seconds (give or take). I was a Tier III supporter among a staff of over 100 persons who supplemented the work of the Tier I agents that actually answered the initial contact phone calls.
* You need to consider hardware requirements as well as software requirements. The COTS packages will each have different operational needs. Most of them will require a central server running whatever they use as a database manager. The odds are that they DIDN'T roll their own DBM, so add a software license for whatever 3rd-party DBM they use, which rolls up into the cost of their offerings. All of them will probably address the networking requirements in order for you to get a specified level of service, and if you have a slow network they will refuse to give you guarantees about response times.
Your HG package would need a decent workstation for each user and a decent in-house network. You might get away with using Access Runtime for them since they won't be developers, but using Access Runtime requires slightly more careful programming. Where it gets interesting - AND expensive - is that if your workload is serving 40 users simultaneously banging away with a high case-load for each, you MIGHT be a bit TOO intense for simple Access. You might be in the territory where an active database server would be needed for what we call a Back-End server. A pure Access solution (native Access front-end and back-end) can cause network load issues when it gets up in user count because Access was designed as a SMALL business DBM solution. At 40 active users, the implied size of the REST of your company means it probably is no longer a SMALL business. An active back-end drastically reduces this load. So you would be looking at a back-end server running SQL Server, ORACLE, MySQL, or any other SQL-based database package that will talk to Access. That machine should be capable of running Windows Server xxxx (don't know the current version, probably 2012) as well as the DBM package, so you will need that machine to have many Gb of RAM and maybe a few Tb of disk storage.
You suggested that you had done enough to believe you needed at least 32 tables. Tables need queries based on the complexity of your model. Even when using the wizards and when building blank-form templates that are partly "instrumented" before you copy and customize them, development with Access isn't lightning-fast.
While you might be very fast and very confident in yourself (which isn't a flaw but might suffer from re-evaluation in a project like this), I would say that you should add half a day to your schedule for EACH two-table RELATIONSHIP that you have to develop. Add a full day for relationships with 3 or more tables. With 32 tables, that number gets huge quickly. You will also need maintenance forms for each table and those tend to take a couple of days each. A report probably takes at least a day once the relationships are set up. Then there are the primary forms needed for your CRM agents and those WILL NOT BE TRIVIAL. Again, even with a template that you can copy and customize, you will have a lot of work for each form.
OK, having given you some practical issues to consider, here is one more that has nothing to do with development and everything to do with business. When you buy COTS software, you are saying that their business flow model matches your own. There is a fine line between "best industry practices" and a COTS package that represents the vision of someone who doesn't work for your company and doesn't know your corporate way of doing things. In essence, you will buy a tail to wag your dog. You have to know that it is a good fit (see earlier paragraph on evaluation) before you make that decision.
Offsetting the implications of that problem, the HG solution has another cost - that of forcing your 40 people to use manual methods while they wait for your HG solution to come up for operations. That is a near-impossible cost to evaluate because it will depend on the quality of the HG package, but the question is "How much extra efficiency will be gained with the HG package?" Because that is the source of your Return On Investment (ROI). If you get a 20% improvement in their work, your ROI is going to be based on 20% x 40 people's salaries representing higher throughput. It might take YEARS for the HG solution to pay for itself, and there is still the chance that if you rushed through the requirements evaluation, you would reduce the efficiency gains.
Good luck. It is NOT a pretty situation. I do not envy you.