I've picked up several F bodies over the years from a few hundred to a few thousand. They used to be a very budget friendly way to get into the Mopar hobby and used to be easy to find nearly anywhere. They respond well to all the traditional small block mods. My last one was an '80 with a '78 front clip. Ran low 12s in Denver.
Unfortunately, prices on these have gone up too and any one you can find that is decently good shape is $10k+ I've seen some Super Coupes and Kit Cars in $20k asking range.
Never paid to much attention to J and M market. Not sure how it looks these days, but I'm sure they are spendy, when you can find them.
As far as M's go just depends on which ones. You can still find some real nice Fifth Ave's since they were mostly owned by older responsible people and cared for. Finding a decent AHB is a different story and when you do they have definitely gone up in price due to availability.
