Hey if you haven't checked out any of the Asian zombie films you might want to give a few a look as I think they may fit what you're looking for. Here's some titles to look for if you haven't done so already.

1. Versus
2. Bio Zombie
3. Bio Cops
4. Junk

There's a few others but I can't remember the titles off hand. There's a couple low budget video zombie films that you might like in Meat Market 1 & 2. They're real small budget films but they're not too bad if you can overlook a lot of the flaws associated with shot on video movie.

Happy Hunting! :)