Free: Contests & Raffles.
Get some National Forest maps and some DNR Public Land maps. The Go Hunt map on the WDFW site also shows public lands- you just need to switch over to the public lands map instead of using the default.
Check out county assesor GIS maps online. BLM maps are pretty helpful in finding larger chunks of public land.
On this topic.... here is a question looking where to find where a GMU ends and another begins... also what if your hunting a border of one GMU and your game runs on to another GMU..... how do you do it.. like GMU 407butts up agains GMU 413 ( Nooksak requires a special permit) So how do you approach that?