http://www.tf2outpost.com/trade/6156323 - Went for 3.5 pure, successfully went rather quickly.

There's not a lot to go on... but at the same time, it's pretty straightforward. Low range would be much more comfortable at 3.5, with a successful quicksale at that point, but it's not too far off as suggested. The one trader who seems serious about what he's doing freely admits he'd take 5ish pure, and with an unusual offer at that much already achieved, it's not an unreasonable expectation.