I bought a ton of killstreak kits for 1 ref each, I got some of them like AWP, Grenade Launcher etc. they were worth 1 key each. But that was when backpack.tf didn't price killstreak kits ;-;
The vita-saw is probably the best melee ever. It's just that 2K might never give the rights for it to be able to sell on the market. Which doesn't make sense since collector's and killstreaks can be sold.