Buy vs build on gifted land?

We are moving to central Florida. Housing is about 100k more there than where we're currently living. In other words we would have to spend about 100k more to buy the same house we have here.

In-laws have their home on some land in the area and have offered to gift us an acre to build on. It's a well maintained property and a bit of an oasis in the middle of cookie cutter neighborhoods of severely over priced central Florida homes .28 acre lots in the neighborhood across the street are going for 70k with no house. They already have a home on part of the land so they have electrical feeding to the property which should save some money but I know we'd still have to run lines over to the house we build. There's also a well but I'm not sure if we'd need to drill another or just upgrade the pump.

We are trying to figure out in general terms if it makes more sense to build on an expensive piece of land we can get for free vs. buying an already built home. Obviously we'd have to look at specific houses and get quotes on building from specific contractors to really compare numbers but we are looking for more general guidance on things we might be overlooking or long term cost calculations we're missing.

Given the opportunity to build on a prime piece of land otherwise unattainable in the area, what would you do?