sig:
Give the rifle a thorough inspection....
Look over all the externals...any cracks, wear, dings, dents? If there are, try to determine if they are superficial or symptamatic of a larger problem.
Take the bolt ouf of the rifle and inspect it. Any gunsmith work done on it? (lapping)? does the bolt face look ok?
To check if the barrel is free-floated, just take a dollar bill and wrap it around the end of the muzzle. Push it toward the action and it should go all the way back to within an inch or so of the recoil lug. I would think the barrel is free floating as most B&C stocks are inlet enough.
Get a bore light and take a look at the inside of the barrel. You should be able to see the lands and grooves from the end of the chamber to the tip of the barrel. If not, it might need to be replaced and could be a negotiating point to lower the price.
Lift the action out of the stock. Inpect the inside of the stock. Any cracks? (interior cracks would be bad)
Does the price include a scope, rings and bases? Look over all those components and consider their condition and quality.
If it includes a decent scope, rings and bases $385 is a decent price, but I'd still try to negotiate lower considering you can buy a brand new Rem 700 SPS for $450 and that would include a cheap scope, rings and bases.
Good luck.