Are there any pokemon prototypes/betas out there? 

I've never seen one come up for sale. I would imagine one would go for big bucks.

SWWWWLLLLL... Big balla money stacks!

I wish.  I'm pretty into game boy protos.  I own quite a few and have been searching them out from all different outlets and I've never seen or heard of any pokemon (R,B,Y) protos.  Some people have found some of the GBA ones but as far as I know, no original game boy.  I'm sure if one did show up it would go for crazy money. 

Also, your best bet for finding one would likely be searching japanese auction sites.  There probably is some from the English translation process but all the fun stuff would surely be found on a japanese cart.   It also doesn't help that they're first party titles either.  First party prototypes are rarer in general for all consoles.

i saw this a few weeks ago...
http://www.ebay.com.au/itm/171399...

ive never seen a proto that looks like the final cart, just looked like he ripped the sticker off.
i wasnt game enough to take a gamble on it.

^feedback on that indicates it was just a silver w/ a missing label. buyer left a neg.

That was one of the most obvious attempts to con someone. It had no indications of being a legit proto...lol

there is always someone stupid enough to fall for a con.

Well, there some interesting design documents out there for the 1st gen games. But as has been said, I wouldn't hold your breath when it comes to finding a prototype of one of the main games, much less a meaningful one.

Bummer.