in any case, you can get new 11spd compatible BB and compact ultegra crankset for $175 or so with free shipping from nashbar, less if they have a sale. if you go 105, which will still be better than you have now, you could get it down to like $130, that's for the cranks and bottom bracket, everything else you could leave alone. it should still work just fine with your 10 speed chain.

because 11spd is so available these days, the 10 spd stuff has actually gotten more expensive.