Can it be legitimate trade?

Here is a good one:

http://www.steamtrades.com/forum/qQDLU/hrust-w6-keys

Better safe then losing $10

Bought from the Steam Russian store or insert location where stuff's cheaper

High risk being:
Seller: Umm alot of people want Rust, i could easily fool one into giving me $10 (his thoughts)
You: I want Rust (your Thoughts)
Trading time-
Seller: i should get payment before i give you game
you: Ok here
Then he blocks you you lose $10 and since it wasnt written down as a contract (like when you buy from ebay ECT) you dont get payapl back. seriously keys are like $2.32 right now 6x2.33 (for average) = $13.98 i think i did it mentally. thats still cheap