Re:
always hard to guess a price to be honest but here's my take:-
the 1994 nickel P7, looks like the important parts are there, the frame/fork/stem/post, cleaned up i would suggest maybe £100 assuming no rust, if there is rust then the new buyer would need to strip and paint or re-plate, and that is expensive so the price would drop (FYI i paid £80 for a 1994 nickel P7 with a bit of rust)
regarding the parts left over, the xtr mech in good condition cleaned up could be 35-60 depending on the jockeys wheels and rusty bolts and scratches.
the rest is whatever you can get.
my advice would be to sell the frame/fork/stem/post/headset as a package, DO NOT SPLIT THE FORK FROM THE FRAME then sell the rest as parts separately, it's a bit more hassle but you'll get more overall, and list prices as "posted prices" as it saves hassle of "how much to post to xyz?" etc.
the modern P7:-
i like this model but it's not necessarily a valuable bike/frame, i consider it to the last of the proper XC P7 frames as after this model it became a oversized long travel hardtail. also it has a 1 1/8 headtube, v brake and disc brake mounts and is designed for a 80-100mm suspension fork so can be built as a nice modern xc bike no problem.
if the paint is good the frame could be maybe £100, if the paint is bad then the price drops.
the fork however is not desirable, they were known to wear quite badly and flex alot.
you said "hope wheels" obviously the hubs are good quality but may need bearings which can be expensive, also this model year if i remember correctly used WTB rims, they were a bit cheap and nasty to be honest and as they will have been used with V brakes they may be quite worn by now, even if they are not worn they are not a set of Mavic rims so although they do the job they aren't desirable as such, the hubs should have disc mounts though if memory serves so that should help them sell. so assuming the wheels are hope XC disc hubs on WTB rims then maybe £100
again the rest of the parts are whatever you can get.
mechs usually 10-30 depending on condition, the chainset if octalink is not popular but if it's square taper it'll sell.
again, i'd suggest selling the frame with the seatpost (and shim?) then sell the rest separately.
hope that helps