Can we sell or give things away for steem on here?? hmmm........

I was wondering what the deal was with selling anything on this platform? I saw an app the other day from the app page, but link didn't work, and then couldn't find it again after that. I do laser engraving, and had an idea to offer laser etched items for people on here for steem tips, in order to help build my steem power on here. I have seen a lottery app before in apps section, but it would be nice if someone could make a lottery like app that we could use in our blogs for "give aways" and "raffles" of our art and services. Something that people would feel comfortable with it not being "fixed" in some way. I heard an interview with the creators from last year, and they said they wanted to have an ebay like function added at some point, seems like it should have been done by now? Confused if maybe there is some snag I don't know about, I assume if was possible though, I would have seen it on here by now?But I have only been here for two weeks now..... Anyone out there that can help shed more light on the subject??

Thanks! <3