Buy a '91 LS400 with Low Mileage?

[DC32]

Hey guys. Wanted to get some info/advice regarding a '91 LS400 for sale. It supposedly has ~41,000 miles and looks mint with basically all of the options the '91 model had (Nakamichi stereo, active air suspension, traction control with heated front seats, etc.). Owner is a collector who claims he got it at an estate sale and is looking to flip it. I asked him for some documentation from the sale or prior maitenance or service records to confirm the mileage (just to make sure the odometer wasn't rolled back or the cluster wasn't replaced). He was asking 12,900 but I feel as if this car could be had for much less. It is the two-tone black color and the paint looks immaculate as well as the interior. Is there anything I should keep in mind price-wise if I can confirm the mileage bearing in mind that this is almost a thirty-one year old car? I am extremely interested in it because I have been wanting an LS400 for a while and I appreciate the look of the first-generation ones more than the later models. 12,900 is a lot to ask for this car and I feel as if I can negotiate it down a few thousand at least. I'd appreciate any advice those experienced with this car can provide.