It's either not a CJ5, or it's not a 1951. Could be a CJ3B or 3A, or any of several other military or civilian variants. Got a picture?
Prices would be anywhere from $50 to $50,000, depending on whole range of issues. As a general rule, early Jeeps are collectible, but not to the point where you will get back the money you put into them.
A "survivor" early Jeep that's been sitting for years, and still has all the original equipment can be a great vehicle. BUT it was basic and uncivilized even when sold new. It will be uncomfortable, very slow, and very unrefined.
A modified early jeep can be anything from pure awesomeness to pure crap.
I guess I'm saying that you need to provide more information!