The thread for DL mileage/MQD run requests is under the Mileage Run Discussion forum -- https://www.flyertalk.com/forum/mile...lp-needed.html

But there isn't much action in that thread these days.

As noted above, you can potentially earn more MQDs than money spent when flying partners due to MQDs being based on mileage flown, but it's probably too late in the year to find any values there. For DL domestic tickets, you just need to look for something in the $1100 range roundtrip (due to US 7.5% domestic excise tax and other taxes on which you don't earn MQDs). Most people would just look for a short day trip in First Class. This shouldn't be too challenging to find.
Booking a DL Vacations package is another option which earns MQDs on package price (less taxes/fees). The other options are to apply for new DL Plat/Reserve Amex card (which comes with annual $2500 MQD Headstart bonus), or manufactured spend on those cards.