Lots of possibilities there. Dead batteries, bad fuel, rodent chewed wiring, rusted internals.
If it's been parked that long with no attention, particularly in the northern states, the batteries are probably toast. If it was parked with less than a full fuel tank there's likely water in the tank from condensation.
On the other hand, you may be able to throw a charge on the batteries and have it start right up. You won't know until you try but better to get it running before you hand over the cash.