FWIW, you can buy the blue PA chock directly from the manufacturer. They're going for quite a bite more though, still cheaper than Baxley's...
http://www.cerka.ca/comersus7f/store/comersus_viewItem.asp?idProduct=45
I bought one from them a couple of years ago, it was $90 at the time.
http://www.cerka.ca/comersus7f/store/comersus_viewItem.asp?idProduct=45
I bought one from them a couple of years ago, it was $90 at the time.