One man's garbage is another man's gold.
I don't think your fiberglass dish is junk, but I wouldn't pay $300 for it, either.
Problem is, a lot of these owners remember the thousands of dollars they cost new.
Well, they're not new now... many want to get rid of 'em.
And they have to pay to have someone take down the dishes and haul 'em away.
So, -
free- sounds like a very attractive price.
Then, you haul it home and regret later if you got a dog. -

The mounts and LNBs are often worth the effort, if you are building up a supply like Linuxman is.
I'm waiting for him to open
The Satellite Shop, any day now.