Neca ninja turtles shredder and Raphael in disguise
 

How much do the shredder and Raphael in disguise go for? Are they still available for sale?

First it should be asked that you're aware these are 1/4 scale figures? Shredder isn't out yet, he can be pre-ordered from various sites. I think Raph came out about a year ago so you'd have to check around online. I think their prices should range around $100 to $120.

So these are bigger than the 4 pack that are on gamestop the 2018 sdcc exclusives right? Are there smaller scales of these figures?

I would recommend starting here http://www.toyark.com/neca-1-4-scale...e-tmnt-175270/

The Raph can be found on BBTS.COM and other sites. I think he is $99ish dollars. Shredder is not out yet. Neither in the smaller configurations. Shredder if ever in smaller size will likely be another 1 to 2 years out.
Again, all but the Gamestop are 1/4 scale (12 inch)

So what scale are the sdcc 4 pack 1990’s movie turtles? Aren’t those the same as the gamestop versions only the gamestop ones are individually packaged?

The Gamestop and SDCC 4 pack figures are in the 7" scale (but being the ninja turtles they don't actually measure in at 7"). The Shredder and trench coat disguise Raph are in the 1/4 scale which puts them at around 18" and 16" respectively (those numbers might be a little off). So far there have been no announcements about those two being translated to the 7" scale.