Unfortunately not a lot. That being said, if they are in perfect condition and all original they'll bring a little more money.
The girls stingrays aren't as collectible.
I'd check past and current auctions on ebay to see what kind of range you can expect. I'd also search google...maybe try the New England Musclebike Museum (located in Bloomfield, CT I believe) to see if they're interested or could at least tell you what to expect for $$.
My GUESS (I said GUESS) is that if they were mint and original and just a girls stingray you'd be looking at $80-100.