If you just want to know the exact location of the land as claimed by the land owner, you only need to hire surveyor to locate the boundary stone only. It can be known right there and then. Minimal cost involve. No need survey for topo or others. It would be waste of money if you decide not to buy it later. Unless you are worry about other issue like how steep is the hill, how wide is the river/drainage crossing the land, any squatters etc. then proper survey needed.

I always hire surveyor to locate boundary stone only because it is very easy to con by people claiming the land is here whereas it is not here but there.