I wanted to do a stroker too. Went turbo, my jimmies have never been faster.
When I was reaearching, the bottom line was that you can piece together your own stroker like jc said for much less.
The big thing that turned me away from an NA build is the extra wear and stress at 7200 rpm+
The piston/valve clearance that some people goof up on with a 288+ cam, and the quality portwork and header design required to optimize the system. Dont get me wrong, if i had 15k to spend on an engine build I would make an NA monster. Id guess that andys engine cost about 6k and has some nice top end pull.
What im trying to say is give me a call when you decide to do a snail