Proof:

http://www.tf2outpost.com/trade/8645060 - two 2 buds offers, TS Max + 8 ref all got rejected

http://www.tf2outpost.com/trade/8043369 - 3 pure (probably collecting), O. Fire milkman + 2 bills + 4 keys (2.3), bubbling noble + crate 40 + s. widow + 20 keys (2.6), Ghost bonk helm (2.3), not even considering Max's, Stormy Crown + Blizzard DeGroot (3.2), rejected 2 buds + 10 keys, Smoking soldier's scope (2.7)

http://www.tf2outpost.com/trade/7596402 - Another 2 buds offer got rejected, searing plasma noble (2.6), etc

So as you can see, all sellers rejected 2 buds or max's head offers. I'd put 2.3 as low range because most offers didnt go below 2.3 unless pure, and would put 3 as high range because one guy offered 3 buds and the other guy offered unusuals around 3.2 and it would be around 3 since he's paying in unusual. Thank you very much for reading my suggestion.