While I agree that prices are getting ridiculous,not sure how your theory of 2 pops in 30 minutes is going to drive them down.
Most SPs charge pro rata more for 30 minutes than for 60. So any savings are negated by the often rushed service you get in 30minute booking. Coming twice in any length booking is a young man's game for most and certainly not possible for the majority on here I
Would imagine.
Find a reasonably priced provider like Posh Victoria or Lucy361 ,both well reviewed and go fill your boots.
Oh and don't forget to report back your experiences here.