Food for thought... Why not just list your 1000RR as a straight up 'for sale' offer, rather than as a 'trade for a specific bike'? I'd think that you'd get far more potential buyers for your bike going that route. Then as a cash buyer yourself you can find a clean, well maintained 250R that you really want.
Otherwise you're simply waiting on someone else who has a 250R (that also meets your criteria) to show up, and who also wants your 1000RR. Just seems like a low probability of that happening.