Rossi has one for about $150, Marlin and Savage go for $200-300, Ruger has one for about $500 and Winchester runs about $800. There are hundreds available on the used market for almost any price you can name. Check out auctionarms.com
No.
wal-mart
Gun stores, sporting goods stores.
Yes you can put a bipod on any rifle.
Gun shop.
Website for gunpartscorp
Blue Book of Gun Values
Go to a gun shop and buy one.
Numrich Gun Parts. and Posibly Midway USA
the rifle, a mannlicher-carcano rifle, is in the US national archives.
The rule of thumb is to buy the best you can afford. "Best" is a meaningless term unless you define what you are going to do, your budget, your skills, etc..
Want ad, on line auction, gun shop, gun shows