That thing is a POS. 15k is extremely pricey. A quad mount is gonna run atleast 20 - 30 k if you can even find one. The rest of the vehicle looks like ****, especially considering it's a "complete restoration" in 88. Parked in 03 under a cover? It's in hot and humid NC, so it's likely a rust bucket now, and I would be surprised if the engine turns over. Not too much work to hook a battery up to turn it over, thats why it is being sold as is, where is because the seller knows it won't run!
FYI, for poos and giggles, we restored an M3A1 Scout Car, and are finishing the restoration of a M2A1 Halftrack. Ground up restorations, as in stripped to the frame, are worth 100k +.