New to CRM – Looking for some guidance

I've read a bunch of stuff on this forum and trialed Hubspot but I'm stuck at the 'I don't know what I don't know' stage.

I'm tech savvy, run my own network and servers and build my own websites. I can figure out self-hosting pretty easily if there is sufficient material on Youtube or vendor websites.

I run a small training company and I want to manage my customers from first contact (mostly via email, Facebook and SMS) through to course attendance and repeat business through evolving training. For instance, client #1 contacts us and wants training at level A so we facilitate that, adding client #1 to a course with clients 2 through 12. Hubspot seems to fail here as I'm trying to use a 'deal' as a training course with clients 1-12 and Hubspot closes the deal after the first client is assigned as 'won'. I then want to use the info to market level B and level C courses to clients 1 – 12.

Integration with Stripe or Square would be an asset, as would a facility to email market through Mailchimp or direct facility.

I'm looking for suggestions on what I should be looking at that is not priced at corporate levels. I'm just a single operator and even with expansion, I still wouldn't need more people in the tool.

What else do I need to tell you guys?