Alot of .22s come to mind, they are usually very over looked for their training/fun uses, Ammo is cheap and if you have a "flinch" it a great way to cure it. A mossy or rem pump (base models) can be had for under 300. Ive seen some REAL nice stoeger O/U shooties for like 325 local, which is alittel over but well with it if thats what your into. For hand guns, a sigma or p95 usually runs under 300, nither are considered "top shelf" by any means, but they a well built and reliable. The sig p6s and former LE s&w 59s run around 250-300 also. A large variety of mil-surps can also be had for under 300, some you might be able to buy 2 even. I check the used racks at local shops often and find myself saying "well if I only had a spare 200 bucks..." 300 bucks can buy alot of gun, as long as you stay clear of the jennings/bryco/whatever they call it now, and the cricket.