Sellers under 0.33 ref

http://www.tf2outpost.com/trade/23456508 - 0.22 Ref Young, I guess it's okay with such a low tier item.

http://www.tf2outpost.com/trade/23450271 - 0.22 Ref Okay

http://www.tf2outpost.com/trade/23450605 - 0.22 Ref Okay

http://www.tf2outpost.com/trade/23472877 - 0.22 Ref Young

http://www.tf2outpost.com/trade/23434362 - 0.22 Ref Okay

http://www.tf2outpost.com/trade/23407292 - 0.22 Ref Okay

http://www.tf2outpost.com/trade/23468220 - 0.22 Ref Young

http://www.tf2outpost.com/trade/23466248 - 0.22 Ref Young

I guess it's okay, though not all are valid.

Unsolds for 0.33 ref/backpack.tf price/more

http://www.tf2outpost.com/trade/23438488 - 1 Day Okay

http://www.tf2outpost.com/trade/23435699 - 1 Day Poorly bumped

http://www.tf2outpost.com/trade/23436081 - 1 Day Poorly bumped

http://www.tf2outpost.com/trade/23429401 - 2 Days Okay

http://www.tf2outpost.com/trade/23428952 - 2 Days Poorly bumped

http://www.tf2outpost.com/trade/23419864 - 2 Days Not bumped at all

http://www.tf2outpost.com/trade/23412525 - 2 Days Not bumped

http://www.tf2outpost.com/trade/23401653 - 3 Days Not bumped at all

http://www.tf2outpost.com/trade/23117292 - 2 Weeks Okay

Conclusion: Meh, I suppose it might just be enough but unsolds are quite vague.