Pete is right about Goodwill. Two years ago I found a Nishiki Sport at Goodwill for $6 ! They had no clue.
Most of the Huffys, Murrays etc. were 15 to 20 bucks as Pete says, but the Nishiki was covered with dirt, dust, and a sprinkling of dried chicken poop (thus the lower price).
I tore it down and completly repacked all bearings and replaced the dried and cracked brake hoods. There was absolutely no wear on any of the bearing surfaces. I believe it had never been ridden, just hung in some barn for years.
I use it only on the local flat canal towpath which is crushed limestone. Always hated to ride my "better" bikes on that surface because of the dust (abrasion).
Last summer I picked up a like new Blackburn mag trainer at the same store. At the checkout they ask me what it was.
Oh, yeah, the price ? $6.