Well, given the triangle of Price <-> Quality <-> Performance of which you can only pick 2, I think BKB’s lineup tends to optimize the performance and price categories. So you can definitely get a higher quality DIY build for cheaper, as long as you sacrifice on performance 
Take for example my single motor hub-board, I’d much rather have it than the Duo:
Small board | Loaded Coyote | 12s1p | Unlimited hub motor
P.S. The regular Duo is 930$, the type R is 1380$