I just received my first order from perfect prey in the mail last week. They have a fantastic reputation and I was pleased with the order and will order from them again. I did find that the vast majority of my lg mice (18-32 grams) were in the smaller range though. Only 4 were bigger than 24 grams.
I would try to go to a reptile expo if you can though. You can buy feeder prey there as well as check out corns and BPs. They are very different snakes, I have both. If you are leaning towards corns, my two cents is to look into Kingsnakes as well. Amazing snakes in my opinion. My favorite snake is my King and my BP is a very close runner up.