price depends on several factors: location, customizability, demand and availability and last but not least whatever people are willing to pay. I've seen keeps sell for 3-20 mil over the last couple of years, the 20 mil being a very rare exception.
scout the land for keep spots, sometimes you get lucky. Alternatively search for Felucca idocs and hope to get the placement. Not sure how the new changes will affect house placement though.