For the upcoming season in case you're looking to get new numbers (or your first set), we used to have a deal with http://shop.rallygrafix.com/ (and if you look in the magnetic number panels you'll notice an SCCV branded option!) We will have to look into a club discount as the past post was from 2005
Finally picked up a set - I have recently inquired about price discount from the past. The discount was included in the posted price as these are SCCV specific on the website, so the cost is as listed ($65 + shipping, or local pickup in Colchester).