An Idea for a crossfire weapon trading system!!

I think it would be awesome if you could put ur weapons up for trade.
For example :
If i wanted to trade away my Thompson, i would put it up for grabs For a number i days i choose,
it would then go on a list where every one can see it,
So people would see that some one was trading a Thompson, and if they wanted one they could put in an offer.
After at least 1 offer has been submitted i may accept one and the trade will continue and be completed.

However as Ive realized there must be some limitations to this:
Permanent weapons can only be traded for Permanent weapons
Temporary weapons can only be traded for Temporary weapons

Possibly:
Pistol 4 pistol
grenade 4 grenade
shotgun 4 shotgun
etc
Or
primary 4 primary
secondary 4 secondary

Another important fact is that Crate weapons can be traded because some people have won more than 1 of the same crate item.
A Reason why this trading system will be so popular is because
weapons when re sold are worth a lot less GP therefore it would be smarter to trade it.

Another point that is perhaps more unlikely is that people can trade ZP for GP Etc...

THNX

XD2Kool4U