If you have room for it (9x7x7), this is the sturdiest, easiest to use, and best value for the money safe I have found. You can get 20-percent off coupons to reduce the price to less than 20 bucks. Bolt it to the floor with carriage bolts from underneath.
http://www.harborfreight.com/9-inch-...afe-94985.html
I also bought one of the Bulldog safes, and they are junk (thin steel) compared to this one.