there are many reasons for speakers to be discounted but in the end it is usually because of market value as a function of sound quality. the are priced at what the market will bear based on their sound quality experience. you see this with used speakers too.
in the case of the SP 888 they are relatively new and have not yet established a need to be discounted.
my personal experiences hearing the SP 8, 10 and 888 is that they are missing that last but important bit of smoothness and refinement in the midrange and treble for my preferences. i caution this by saying it could be related to amplifier and system synergy but it was there nonetheless.
what value is a discounted speaker if it doesnt meet your sound quality objectives?
buying with the ability to return is a smart move. for my money there are at least two other comparably priced speakers that I would try first.
good luck.