A full scale POS system (in the tens of thousands of dollars) is very very much overkill, however there's a few products out there that are smaller in scope. One of the main products that I'd suggest is Masterpiece, an art gallery software solution that a few antique stores use. I used to do support for them and do lead gen now, so give me a call and I can explain to you how the system works. Its priced more or less affordably as well and has a huge amount of positives.