Have you tried AutoTrader.com or Cars.com? It seems much easier to find a specific car that way, as you can filter down to what you want...
Using a random Pittsburg zip code, I see gray for $23,000 (AT-13A44C2D) and blue for $28,500 (AT-138D3950). If the seller is motivated to sell, you may be able to buy for less than $28,500. And that blue is such a nice color...
Find Your Car: Porsche Boxster Listings Near Pittsburgh, PA 15201 - AutoTrader.com
Of course, like you've already mentioned, many more available in black and silver. And even more that aren't an S.
Good luck with your search. Hope you find your perfect match, at a reasonable price.
