[JWheaton]

This might not be as accurate, but it is a thought as to why more SPF's on the market.

Beyond the fact that more than double the number of SPF's v/ ERA being sold, I think the typical buyer for an ERA and SPF are different.

SPF's tend to be sold to poeple who want more of a turnkey experience. Buyers certainly get involved with engine and tranny choice.

ERA buyers get involved, or even build, a good portion of the cars themselves.

SPF's tend to be sold and bought by those who have the passion to drive. ERA's tend to have buyers who want the build and driving experience. (in general, not all cases)