Play institute a loyalty points scheme.
I hope they pay royalties to MVM for the idea.
They've instituted a loyalty scheme, spend a pound, save a penny. What you save can be spent on future purchases.
Accumulating points gives you more to spend obviously, and you can use them in part payment as well complete (should you accumulate enough)
You have to spend at least once every 180 days at Play to keep your tally of points active, otherwise they'll be deleted.
http://www.play.com/superpoints.html
http://www.play.com/Helpdesk/SuperPoints_FAQ/SuperPoints_FAQ.aspx