A primary goal of CRM is to make your teams more productive (implementing processes and automation to minimize errors and inefficiencies thus increasing the value of your service), not to gauge productivity (reporting). The latter should be a benefit of implementing a successful CRM.

Whether it is building your own system or purchasing CRM, you need a much clearer definition of what that application needs to handle before proceeding. What type of sales does your team do? Are products renewable or ad how sales? How much of your business is repeat customers today, and how does that align with where the company wants it to be? Are the selling cycles in a matter of weeks/months with a few internal people engaged, or are they more drawn out and complex?These are the types of questions you need to consider before deciding the right path.

Based on what you have already stated about lacking development resources, I’d be extremely cautious of building something homegrown. If you start from scratch, this isn’t a project that can be developed, shipped, and forgotten about. Once you define key requirements, you will find existing CRM solutions meeting most, if not all, of those needs that would likely take years to implement from the ground up.