Check out the link on the bottom of Rawfeddogs's posts, it's chock full of useful information, pretty much everything you need to know about feeding raw and getting started.
I think the normal recommended amount is 2 - 3 % of the dog's ideal body weight and then monitor it from there like if they're gaining weight, cut it back, if they're losing weight because they're really active or have a fast metabolism, add some more. Try posting an ad on craigslist or asking your neighbors for any of their old meat from their freezers they don't plan on using, I acquired about 10 - 15 lbs of free meat that way today (venison, chicken, and rabbit mostly).