I would have to agree to disagree with mr. deer hunter. While you can get great guns at great prices on the used racks, you can also get someone else's problem. There are some really nice bolt guns out there in the $300-$400 range right now. You certainly can buy nicer looking rifles for more money, but you won't buy one that is more accurate. The guns I would look at if you're on a budget would be the Marlin XL-7, Savage 110 or 111 with the Accu-trigger, or a T/C Venture. The Savage with accu-trigger will likely put you up closer to the $500 mark though. I have owned a few of the Savages with accu-triggers and all have been great shooters. I also have a Venture, which is also a great shooter with a great trigger. It also is guaranteed to shot 1 MOA. I haven't shot a marlin yet, but have heard awesome reviews from everyone I know that has one.
As for caliber, the .270 is a great deer cartridge. I hunt with a .308 and occasionally a .243 which are both great rounds as well. Really anything from a .243 to a 30-06 would be plenty of gun for deer. Anything over an '06 is pretty much overkill unless you're shooting long distances.