As already mentioned above, take a look in TK Maxx. They often have some nice cast iron pans of various sizes and are very well priced. The main thing you need to look for is casting quality and check that the metal is a nice even thickness throughout.
Then when you get it home, even if it says pre-seasoned, just season it anyway. Bacon is always a good thing to cook on it as it seasons the pan and you get to eat some bacon! You'll know it's well seasoned when you can fry an egg without it sticking! Cast iron pans are amazing if used correctly, the more you use them the better they get! How many more times can I fit the word 'season' in this paragraph!
I can also vouch for the ronnie sunshines dutch ovens. I have three of them (different sizes!) and they're all very good.