How business customers database do you use ? Is possible to do it in Apple Numbers ?

Hello. Whats the best way to make customers database ? Exist something from Apple ? It must be connected with Apple numbers, because my company warehouse is running on it, and I see there my profits and things like that. I'm searching for some free solution, because have only small company just now, but my budget can be to 5$/month. Thank you very much for your help :)