While it might be in the BlueBook range, I think it'* a little high for a 1999 N/A 3800. FWIW, my 97 needed the intakes done twice so far: Once around 45K and again around 85K. You really can NOT predict it, and the Dex-Cool coolant appears to make the problem worse in a number of ways, so if you buy it, I'd ask you to seriously consider changing it over to green coolant. (I haven't changed over, yet, but I have no love for the Dex after two intake jobs.)
If it were me, and I were going to spend north of $7000, I'd personally get a 2000+ model, even if I had to spend a little bit more coin to get it. Don't get me wrong, I own and love the 96-99 models, but they're 8 years old now at the newest, and while *far* from being obsolete, I typically keep cars around 12 years, so if it were me, I'd start out with something a little bit newer. In fact, the last two cars I bought; -my `97SE and my wife'* `01 GP GT, were each only 2 years old when I bought them, and I've been very pleased with both cars.
97 SE, teflon wiper blades, Dunlop Sport A-2 tires, Leather steering wheel cover, Pioneer DEH-P480MP mp3 CDRW head unit, Pioneer 12-disc changer, iPod hookup, Boston Acoustic 3 way 6x9'*, Boston acoustic separates in door pods, Alpine 4 channel amp in trunk. Magnaflow dual outlet muffler and Ractive stainless tips. Autozone rice pipe and K&N 4750 intake kit. Clear corner lights. Energy Suspension end links.