NSX is no longer a popular car here.
For maintenance parts, one can buy from DCH, the official Honda dealer. Or u can buy from the indies as most parts are same as older Accord/ Legend.
For performance parts, most of us buy direct from Japan if u hv friends. Or from SOS from AZ.
Body kits are seldom found here in stock. Check 28 car.com under parts section, u may find parts from scrapyards which there are plenty.