I've never made tortillas before, either, but yesterday I ordered 5 lbs of heirloom corn from this website.
I'm planning to do the whole process of soaking the kernels in slaked lime solution, and making nixtamal. I watched an Alton Brown episode where he did that, and it didn't look that difficult. Everything I've read says the corn flavor in homemade tortillas is to die for. And apparently they freeze well, too.
But if you're not interested in going to that much work, I see they also sell masa harina on the website.