Stepahanie,
Series land rover parts are generally quite reasonable and very available.
Sure, a rebuild on a transmission is going to set you back $1500-2000, but you can find a used one for $200. There are clubs all across the country and series owners are usually very helpful and willing to part with spares on the cheap.
Brakes are very reasonably priced as are the electical compenents and pretty much everything else. This one appears to have had the expensive stuff (frame, body, paint, interior, swivel balls) mostly done. They are also incredibly easy to work on and dead simple to repair.
On the other hand, you better be able to fix one on the side of the trail as they are somewhat maintaince intensive.
Ron