The current Target deal isn't very good IMO. They have much better ones - wait for them. My 'goal' price for disposables is .12/diaper - I won't buy at more than that unless I'm desperate (then I'll accept .14-.15/diaper). A great price (once a year bargain where I stock up) is under .10/diaper.
Up & Up is cheaper than amazon mom or any of the other name brand. What I do is wait for when Target discounts their biggest cases of diapers. This is the site that I follow for good diaper deals: http://www.babycheapskate.com/
She does weekly diaper/wipe deals. I've noticed that the 'stockuportunity' prices aren't necessarily always low enough, so that's why I go for the .12/diaper as my 'buy' price.
Mom of 4: Boy (10), Girl (7), Boy (4), Girl (2)