Sumbawa is the island next to Lombok and it runs a step behind on everything: fewer people, fewer services, and land prices that no longer exist on the other two. It is where you still get to pick the plot.
For the buyer who wants beachfront and wants to build it their way, and accepts a longer calendar for it.
Long sand beach, hills looking out to open ocean and several surf breaks. On the west coast you can still buy land metres from the water for what the paperwork alone costs in Bali.
Almost nothing is built here: you buy the land and put the house up. That is cheaper and lets you choose the house, in exchange for permits, a builder and site visits. If you do not live there, the thing to settle before buying is who runs the build on the ground.
By ferry from east Lombok, or flying into Sumbawa Besar. There is no international airport and no designated zone: it is the least developed of the three, and that is why the land is at this price.