Since you say something more connected to Bitcoin, how about like a Bitcoin education center? You could offer workshops and courses and probably one-on-one training on Bitcoin (how it works, what to do, what not to do, etc). I haven’t thought so indepth about it but maybe you can think about it and work with it. It mustn’t be something huge too. It could be in your store and you don’t have to actually call it an education center. You could print handouts to give to some customers too.
Teaching bitcoin to others is a good idea but to do that you need to have enough knowledge, experience or even deep expertise to be able to teach others and take their money. You can't take advantage of people's ignorance and give them knowledge about bitcoin when you yourself don't have too much knowledge about bitcoin. Not to mention, knowledge about bitcoin is not too difficult to find on the internet and everything is free. So if you want to open a center or a class to teach about bitcoin, there is nothing wrong but you need to provide them with knowledge commensurate with the amount of money they pay you. Education may sound simple but it is no simpler than business related to bitcoin.