acomplishments and the feeling it brings

So my boyfriends little brother just had a birthday and his mom asked him if he could create an invitation for his party, my boyfriend was going to accept (i think) until I swooped in and said "OMG I have the BEST idea for the invitation I'l do it!!!" So I began to work on his invitation. He wanted a zombie party so of course I had to make him into a zombie on his invitation, so that is exactly what I did. Naturally the kid absolutely loved it, and now I'm being told I should sell custom made invitations on ebay. So I am really considering it. I am pretty excited about doing it, but I am also quite worried about people not liking them. What if no one wants to buy them? I end up second guessing myself so although I have been thinking about doing this all weekend and now almost all week I still haven't decided if I want to do it. I am scared it won't work out the way I want it to. What if people don't like it? I am scared of being rejected by complete strangers. I think I need to just get out there and do it. But what if I can't?