Hi Michelle and welcome to the forum,
I personally really love this field, absolutely perfect market space to be in, especially if you have a creative flare you can exploit.
Tony29 has thrown up a suggestion there for you and there is no shortage of suppliers doing this type of thing now, where it seems not too long ago, it was hard to find anyone outside of Cafepress ..... how times have changed :)
I think you will find this blog helpful Link hidden: Login to view
In regards to printing inventory, Link hidden: Login to view probably goes close to offering the biggest and most versatile stock profile to exploit, but I don't think they drop-ship (could be wrong) Price with them may also be a factor because of how they position themselves in the market-space.