Land cost depends on the location. You can find an acre of rural land for $1K. Or an 1/8th acre for $1M or more in a city.

For a cheap parcel of land in an unincorporated area with no building permit process, but with existing grid power, you can buy and build quite reasonably. (There are several YouTube channels covering builds like this.) In these areas, I wouldn’t overlook existing properties as well.