Tom,
I would say it is safe to buy a car that has been through an auction. Having gone through an auction doesn't change anything about the physical and mechanical condition of a car. Just have it checked thouroughly by a ACURA dealer or someone who knows NSX's. Manheim does represent their cars as best that they can. A good NSX can be found anywhere, I don't think that the ones sold at auction are in particularly worse condition than anywhere else. As with any sample group, there are bad ones and there are good ones, just like in the retail and private party markets. I have bought cars from that particular auction and haven't had problems with them. Generally, Florida cars are usually in much better condition than those from the east coast and pretty much anywhere else except CA. Mileage tampering can be found everywhere, not just at auctions, but I assure you that the auctions regulate it much better than a private party would. Manheim is owned by COX media communications which is a huge company that probably owns many of your tv stations. Cars are sold with certain announcements as to their condition. Frame damage, title issues, and True Mileage Unknown all must be announced or the buying dealer has recourse to return the vehicle within a certain time frame. If you trust your friend and his knowledge of buying NSX's, it could be a good deal for you. Many NSX's go through the Hiline auction that you mention. I would not suggest going with some stranger who is trying to make a quick $500 off of you. Think of what will happen if you have a problem with the car. I guarantee that you will not be taken care of. The practice that people often talk about with dealers that charge a $500 fee to buy for you at auctions is frowned upon by all reputable dealers as well as the auction companies. It is usually done by unestablished dealers that are trying to make a quick buck and then run and shut down when there are problems. Those dealers are basically skirting around all the auction and DMV rules by doing this. Just take the usual measures to protect yourself to make sure you don't get burned. Salvage title and cars that have been wrecked can easily be spotted by a professional regardless of what the dealer, auction, or title says. Cars with tampered mileage would usually show up on titles and on Carfax. I have found Carfax to be pretty accurate with odo rollbacks but not on accident history. Mileage issues are usually on older cars. Just be cautious. If something doesn't look right, like it shows more wear than you think a car of xxxx mileage should, than it proably isn't xxxx mileage. If the deal sounds too good to be true, it probably is. You can really get burned on a purchase of a car such as the NSX, so just be careful and use all the resources available to you such as this website.
Chris