There are oodles of quality options around the $100-130 level.
Nook HD, as mentioned, the 1st-gen Google Nexus 7, the Sero 7 Pro (available at Wal-Mart), and the Kindle Fire (non-HD).
My kids happily play on our two HP TouchPads (with Android installed). Having just checked Craigslist, I'm shocked at some of the prices being listed.