I'll add some actual shop information to this page soon™, but people have been frequently asking for the drop %s.
This table describes, for a given day, what the likelihood is of seeing a given tier of item in a typical shop.
DayBronzeSilverGoldDiamond
1100%---
290%10%--
380%20%--
470%30%--
555%40%5%-
640%50%10%-
730%50%20%-
825%45%30%-
910%40%40%10%
10+-30%50%20%