There's quite a lot of support for the ol' P4. Internet and credit card will get you service items, although serious restoration is best handled as locally as possible. You may find the doors, for example, are aluminium. The 60 was right at the bottom of the range, with a four-pot engine that's really Land-Rover. So no trouble getting engine stuff! However it's a heavy car for so little power.
As for price, my motto has always been: pay as little as possible! For a total project, I wouldn't go near 4 figures, and I'd be wanting 3 to be as small as I could get them.
If you do go for it you will end up with a roomy luxury car; up to you what you do about the power issue. The interior is walnut and leather, so make sure it's complete. Restoration of that isn't cheap unless you can do it yourself. Make sure also that the windows are intact, as the rear screen is in 3 curved pieces.
Good luck!