The card industry is extremely competetive. I wouldn't go to a printer until my client base was up and running. Printing small quantities is very expensive, and printing large quantities means a whole lot of undesireable inventory. However, you could set up a cafepress.com shop and get your stuff on not only cards, but also on shirts, clocks, mugs, etc. and it won't cost you much of anything on a yearly basis. That way you could spend your time and resources marketing.
Another option is to print your works on really good paper (for example, a heavy watercolor paper or canvas paper) and get out the ole exacto knife or guillotine. A tiny gold label with your biz name, and there ya go. Saves on inventory (you only print/cut what you need), but it can be time-consuming.
How does Cafepress work exactly? Can you sell Cafepress items through Ebay? I get more customers on Ebay than anywhere else and have recently sold my paintings for over $50 and have sold 3 paintings to the same person, so if I could make prints of them, I think they would do well.
I dont think I would do well with the exacto knife and printing them myself, I have no patience. Right now, I was thinking of contacting someone who prints club flyers and maybe having them print up postcards of my stuff. I would be interested in Cafepress though too...so if you know anything about how to sell on there please fill me in. I am clueless lol.
PS I would love to see your work, send me a link to your site