First let me say I agree in this economy everything's harder but certain items do not apply - luxury items such as our NSX or even cars in general are LUXURY items! thus any buyer looking to buy has disposable income so this should not be a real factor.
Example: Buyer is looking at a $60k NSX ~ he obviously has money to play with so nit-picking over a few grand shouldn't be an issue.
As for mods, clean simple bolt on mods are easily worth at least 50% maybe more of what the original owner paid. If you plan to low-ball me / him for those mods, I'll just remove it and put the car back to stock and sell the parts separately. Everyone knows this and it's up to the buyer/seller to agree to a "fair" price.
CRAZY MODS: Anything requiring new paint, drilling, removing fenders, FI of any sort, cutting wires or non-reversable mods are a totally different animal. At this point you just narrowed the buyer potential pool to a very small margin. I agree with the OP on this area in that extreme mods will kill the value in most cases as people can never trust the mods were done correctly, etc.
Anytime you do extreme mods, you severly limit your buyer pool since you would have to find the exact buyer who will appreciate the modifications you made.
General rule is to keep all stock parts when you mod so you can return it to stock if need be. If you sell those stock parts then you are SOL and at the mercy of the new buyer.
For my personal NSX, every modification is well documented with receipts and can be reversed. It's actually a bonus for me because the OEM seats are wrapped in plastic in like new status for the new owner if the need arises. Everything else I have on the car can be removed so it's a win/win for me
rick
P.S. I 'd like to add a bone stock virgin NSX is only valuable to collectors or a small majority of people on this board. Most of us enjoy some level of mods which is why we are on here in the first place! Thus for people like me and many of you, small mods increase the enjoyment of the car and are a big PLUS!
Agree or disagree? hehe