Why TF2 items are so expensive?

[Big Donkey]

I ha been looking to buy some tf2 items in the steam(not in games item) some of them is very cheap, but some of the are very expensive, because they have a red name or orange name, so they are much expensive than a blue name, which is same item , but with different colour name. i want to ask what is the different? why thep price so much different between two same item with different colour name? they have the same effect like damage....... are people stupid?

[some react developer]

It's all arbituary

[GoldenOuji]

Agree

[papapyro]

lol'd. do u even economy

[Magical Purple Man]

Items with Red names are items that require 100/200 items to craft a collectors quality of it
(no example here as i don't have one)

Items with Purple names are rare hats that can only be acquired by random luck when opening a crate, and there are some pretty cool effects which make people want them. (There is an unusual weapon that you can get when the halloween events come around, it is un-tradeable and is only worth around 1 key so it isn't worth that much)
http://steamcommunity.com/id/givememanyseed/inventory/#440_2_1133888815

Items with Blue names are items that were around before a certain update (not sure which one) and can no longer be obtained in Vintage quality now, they aren't very sought after
http://steamcommunity.com/id/givememanyseed/inventory/#440_2_2057773447

Items with Green names are items obtained through a pre-order bonus
http://steamcommunity.com/id/givememanyseed/inventory/#440_2_1563142042

And items with Orange names are stranges and count kills/ sentry kills/ ubers etc depending on the weapon and some weapons can no longer be obtained in strange format and are exceedingly rare.
Stranges can't usually be sold on the market as they are not marketable material, but now with the Killstreak kits items can now have additional effects on them (only specilized and Professional killstreaks do this though and they have to be made first) and they become marketable.
I have an example, i have this
http://steamcommunity.com/id/givememanyseed/inventory/?modal=1&picker=1#440_2_2124596309
And ATM looking at the market there is only one other one on sale and it is currently being sold for £9

Edit: updated with some examples

[Tomboeg]

Rarity. As for 'strange' they count your kills/actions.

[Universalerror]

To add to Lil Guardian Pyro's great comment, vintage items are items that were owned by players before the mannconcomy update when the store was introduced. I've also heared that you get any items replaced by steam support in vintage quality. I don't know the last one for certain though.

[Long Ago [Linux]]

Strange bot killer weapons are available on Steam Market. They only count real player kills unless you add strange parts to count robots killed, etc.

I got this one there:
http://steamcommunity.com/id/efflandt/inventory/#440_2_1959773483

[erblung]

Originally posted by Lil Guardian Pyro:

DIDNT READ LOL

+69 a lot of effort put in

[Magical Purple Man]

Originally posted by ultraman_12 TH:

Originally posted by Lil Guardian Pyro:

DID READ LOL

LOL I DIDN'T READ!

Originally posted by LoveTina:

which is same item , but with different colour name. i want to ask what is the different? why thep price so much different between two same item with different colour name?

I did answer (one) of his questions.
If you actually read the OP you would know

[erblung]

Originally posted by Lil Guardian Pyro:

Originally posted by ultraman_12 TH:

DIDNT READ LOL

ultraman ftw!

wtf hax0r facestap aimboat reported

[Magical Purple Man]

Originally posted by ultraman_12 TH:

Originally posted by Lil Guardian Pyro:

ultraman ftL!

wtf hax0r facestap aimboat reported

OMFG WTFBBQHAX!
Repotted to Volvo

[erblung]

Originally posted by Lil Guardian Pyro:

Originally posted by ultraman_12 TH:

wtf hax0r facestap aimboat reported

OMFG WTFBBQHAX!
Repotted to Volvo

VuIva*. I request for everyone in the world to change volvo to vuIva (vuIva means something)