Good lord....15k for 12s????????
Explorer/GT40P head long block, a good intake setup (either a good carb setup or good EFI), a good cam to match everything else and at least 3.73 gears with slicks and a 5 speed.
I've seen this combo go as deep as 12.50 in a coupe with a dialed in suspension w/air bag and 90/10s.
Total cost? Well that depends on the Explorer engine and weather you get all your parts new or if you take your time and look through some classifieds and get things cheap. We have a guy on our forums who has about 3k into his hatch and it's running high 10s right now, mainly because he got parts for cheap and because it's built right and with matching parts.
Oh, and if i can run low 14s with my busted ass bone stock '85 long block, then i guess it's going to take that 15k to shave off 2 more seconds huh? Well for 15k i have a PLETHORA of options...
1) all forged internal stroker...MAYBE 5k...which would leave another 10 for a nasty 300hp 2 stage nitrous system that would probably put me somewhere around high 9s.
2) the afore mentioned setup, plus the nitrous, or a supercharger, or turbo....bet yet how about a junkyard turbo? Here
http://www.cardomain.com/ride/2207793 is my buddy Chris's coupe....the car has had a bunch of recent changes but it's a basic junkyard turbo setup, making 533/611 and is pushing low 10s. Price? you wouldn't believe me if i told you...