Yep, that's also very interesting option. I've just managed to find some availability on SK with also very decent surcharges (less than 40E) and they're flying to ORD with their fresh A350. But they opened availability only till February.
Anyway I'm okay with paying around 100EUR (that's pretty common price on UA) to 200EUR (Turkish), around 300-400EUR seems to be quite unreasonable, at least for C.

I'll need to think about it. Maybe I'll book some safe option and then closer to departure I'll try to rebook it(cancel & book another flight). Award flights are still refundable for a fee of $50, right?

Big thanks for your input PVDtoDEL!