Whilst i am at it, as a rule, never accept a deal on offer in local chat - 99% of the time it is a scam.
It took me a while to see the scam in the example below.
The seller was offering to sell a Plex for 585m ISK when the market price was 625m ISK. At first glance, that is what appeared to be on offer . . . . . . until i read it through several times: I would pay 585m, i would get 1 Plex, and then i would pay a Plex . . . . . in other words i would pay 585m ISK for nothing. A very simple scam but deceptive in its simpleness! It took me a while to see the "You Will Pay" part at the bottom.
The seller is offering to sell three several items for a price of 549m ISK.
A market check of the Imperial Nay Energized Kinetic Membrane looks interesting, these items may sell for 655m ISK each:
But the history check of the price reveals the scam: