Rich, been detecting for many, many years, and yes, there are some truly amazing finds to be made in W. Wa.
Unlike the east coast, we don't have the 300+ year history that they do, so if you're got your heart set on finding as seated liberty qtr., well...it could happen, but you will find coins going back to the 1880's if ya look in the right spot.
A "cheap machine" has it's limits, both in depth and discrimination. The ground here is very mineralized, so being able to ground balance is critical. A cheap machine like a low-end Bounty Hunter you bought at Fred Meyer won't get ya much, but it will go off when the coil goes over metal. A decent machine (still on the lower price end) will run you about $300, and a top-end machine can run $600-$2000. All depends what and where you want to detect.
As for finding the "good stuff", well, "good stuff" varies from hunter to hunter. If you're after relics of times past, check out old logging camps and do the research to find out where events took place back in the old days.
It's all about location, location, location.
With only 20 hrs. out, you've barely got used to the detector. It's a hobby where you can find cool stuff, but you're not going to get rich doing it.
Check out
www.treasurenet.com, as they cover every aspect of treasure hunting from the Lost Dutchman to shipwrecks, metal detecting to prospecting and plenty of forums where your ideas on Bigfoot will be well accepted.