Reply to Where to get 'extended version' of top40 pop tracks?

I feel dumb for asking this.

I gotta dj for a bunch of friends for a birthday party, and I usually get my tracks from beatport and itunes, but for a lot of popular top40 type tracks; but for the great majority of pop tracks available on itunes; they never have any 'extended' mixes of the tracks available; its always the short 3-4 minutes radio single

Those radio singles are 'workable' but sometimes, damn I wish they had some breathing space ; I checked those promo only type cd pools one of my friend is members of, and the 'mainstream release' albums are the regular radio mixes and the so called 'club compilation' are super lousy remixes of pop tracks..

So I was just wondering if there was a legit ressource online for extended mix versions of pop tracks? Some radio mixes are kinda short-notice if you know what I mean.