What class do you plan on running in for Viper Days? Super Stock, Prepared, Modified, Super Modified, Unlimited? That would dictate what type of track car you'd be looking for.
If you run Unlimited, then you can p/u a used VRL car. The prices are right for these cars as the owners have already received their Comp Coupes. The classifieds on this site has a few as well as the Viper Days site.