There's pages of sellers without recent sales on outpost selling for 3 and 4 keys.

Selling for 2 keys:

[url]http://www.tf2outpost.com/trade/5745493[/url]

[url]http://www.tf2outpost.com/trade/5741355[/url]

probably can find more sellers between 2 and 3, but need to sleep.

I can find many sellers trying to sell now on outpost within my price range and still remaining unsold for awhile, which should mean that my suggestion is more accurate now than the old price which is 2 weeks old. Buyers that say they want to buy for 2 keys also seem to have luck as shown in my other links.

Someone selling for 2 keys 2 ref, Gen staff with name tag

[url]http://www.tf2outpost.com/trade/5754826[/url]

This guy selling his for 2 keys 1.66 ref:

[url]http://www.tf2outpost.com/trade/5720766[/url]

This guy seems to sell for 2 keys only if you pay in refined, but not keys:

[url]http://www.tf2outpost.com/trade/5651712[/url]

2 keys plus 1 ref:

[url]http://www.tf2outpost.com/trade/5697463[/url]