I have a black SRAM S500 Chainset. Which I reckon would be pretty much the same spec as a 105...
This came off my boardmans team carbon road bike, i belive it's a 50/34 as well I'm not sure on crank length but the bike is a medium so what ever would come with -a bike that size.
The chain rings have been used for about 1500 Ish miles, so plenty life and comes with bottom bracket.
Yours for £45 ! I'd need to work out postage costs... If your close to Birmingham or London I may be able to deliver or anywhere in between..
Thanks