For ticket management or knowledge bases I would lean toward using open source or paying for a service. For CRM (or anything else) if it's something unique/val

For ticket management or knowledge bases I would lean toward using open source or paying for a service. For CRM (or anything else) if it's something unique/valuable to your business where spending some development time would bring value and time savings then go with something custom. It would help if you have a development team that can build it quickly (Rails/Laravel) so the cost/time doesn't get out of control. Building the basics and adding needed features would work well.