Do I add on strange parts to my price when selling weapons?

[KennyAtom]

So I have a medigun with a "Allied Healing Done" strange part. Backpack.tf says the part itself is worth 2 keys, do I factor in the price and if so, to what degree?

[Scott Bakula]

An attached part will never be worth the same amount as an unattached one.

 

As for how much it adds, it's both dependent on the part and the person. In this case, it's at least a popular part so there is demand for it. You'll probably be able to get an additional key out of it.

 

One popular method for selling parted weapons is auctions, with the general idea being "take what profit you canget  now instead of sitting on the item for a potential profit".