A quick scan of recent solds, the lowest was about of 85k, but that was a infill lot, not in a newer development, and in washougal. I did also find, closer in (vancouver) a culdesac of lots, also in that price range....otherwise most seem to be listed around 110-130k.
Many factors determine a price, area, utilities available, degree of development, HOA or no home owners, and even the CCR's specifying what can be built.
I hope this gives you a general idea......A realtor can provide you with more specific information after an interview to determine your goals and objectives and a best match result.
Jensen White Realty Inc.
That should give you an idea.