The Vizio 8" tablet is excellent. It has a 1024x768 screen, and comes with the Android Market installed by default. Great sound and battery life, too. You can pick them up for $198 from Wal-Mart.
I have had bad experiences with the Coby Kyros tablets. I got one of their 8125 tablets, but had to return it because the wifi didn't work. Replacement was no better.
The Vizio blows them out of the water and is nearly as cheap, so why bother?