Mech Bunny here.
1500 for unlimeted copies and first site is sliced and integrated for you.
or
500 per copy and you must do all design integration. Or hire it out for 1k to 2k per site.
No brainer for me anyway.
We'll see how STP develops over time but right now I havent seen any large sites running it while Mech Bunny script runs on sites with millions of hits per day. I did see STP just released a nice default design which will definetly help but if you want to customize it then the above still applies.