TF2 does have somewhat de-facto items serving as currency, although none of them offer any specific gameplay advantage. They are:
* buds (limited apple Earbuds given for a short period of time): These are worth roughly 2 bill's + some keys, or 24 keys.
* bill's (Bill's Hat, also given for a short period of time for those that preoredered left 4 dead 2) worth around 8 - 10 keys
* keys worth around 2.44 to 2.55 metal
* metal
Everything else is measured around these 4 items. All these prices seem to come from a single source. The "TF2 Spreadsheet", a google docs spreadsheet, created by "the powers that be" which seem to have defined these prices somehow.
It is not a perfect system though, because what generally happens is the values are used as a starting point for a sale. Whoever's selling wants more, declaring that the spreadsheet prices are only a reference, and they know their item sells for more. Whoever's buying usually ridicules the seller saying that the particular item will never sell for the spreadsheet price, which is already outdated.
How trades are made with this system, I don't understand. For those not wanting to deal with all the chaos, there's http://www.tf2wh.com/, which seems to have a rigid credit currency set. Of course it helps that most of the trades are done by bots, so no human interaction is required.
* buds (limited apple Earbuds given for a short period of time): These are worth roughly 2 bill's + some keys, or 24 keys.
* bill's (Bill's Hat, also given for a short period of time for those that preoredered left 4 dead 2) worth around 8 - 10 keys
* keys worth around 2.44 to 2.55 metal
* metal
Everything else is measured around these 4 items. All these prices seem to come from a single source. The "TF2 Spreadsheet", a google docs spreadsheet, created by "the powers that be" which seem to have defined these prices somehow.
It is not a perfect system though, because what generally happens is the values are used as a starting point for a sale. Whoever's selling wants more, declaring that the spreadsheet prices are only a reference, and they know their item sells for more. Whoever's buying usually ridicules the seller saying that the particular item will never sell for the spreadsheet price, which is already outdated.
How trades are made with this system, I don't understand. For those not wanting to deal with all the chaos, there's http://www.tf2wh.com/, which seems to have a rigid credit currency set. Of course it helps that most of the trades are done by bots, so no human interaction is required.