I like the "B" concept but is lacking some additional element of overall design to be front runner like circle background on "U" or something else that makes the logo a bit more impactful.
Same with #47. I like this and have that other element with the shopping price tag concept. Maybe something like a fist showing power/winning.
We're not just about "buying" we're about quick winning deals and buying them before they show up on other peoples computers. Buying is a given and want to more focus on speed, winning etc.
I like many of the others but these two had good elements that seemed to fit out audience.