I agree with most everything that's been said here. The SKS makes the most sense in my opinion though. You can get a SKS for around $200. That leaves plenty of money to purchase two or three tins of 7.62x39 to put away and another one to shoot. Plus there are all kinds of accessories you can add on to them.
Another rifle I'll throw out there is the Little KELTEC SU-16C. It's a pretty neat little .223 rifle that accepts AR mags at a little over half the cost.
http://www.kel-tec-cnc.com/su16c.html
For a cheap bolt gun, I might consider an Mosin Nagent. You can pick those up for around a $100. Yeah I know their old, but most of the ones being imported into the country seem to be very reliable and accurate. Ammo is cheap for them too. A lot of the M44s look to be in excellent condition. It's hard to beat the price on one.
I'd also consider a 30/30 lever gun. Ammo is plentiful and as someone else pointed out, they aren't very scary looking.