I don't do mileage runs per se but I've been able to fly 50k qualifying miles by often finding TATL fares for around $800, sometimes less, during the offseason.
Those days seem to be gone though, as flying even in January or February, it's hard to get under $1000 these days.
I got Gold status on UA this year by buying 30k RDMs and PQMs early this year and doing 2 instead of 4 TATL flights.
We'll see if the accelerator purchases count as PQDs next year ...