Not everyone likes the BB30 standard. But they want to buy a frame that has a BB30 bottom bracket shell. No need to despair, get the frame and then purchase SRAM's BB30 to BSA Bottom Bracket Adapter Kit. Once it is pressed into the BB30 shell, your bottom bracket will function like any other English-threaded bottom bracket. Install your favourite external bottom bracket or your favourite internal bottom bracket.
This isn't an easy home install, so you might want to take it to a shop. Claimed weight of the SRAM BB30 To BSA Bottom Bracket Adapter Kit is 60g.