Certainly many sellers on here are using bots, or just purchasing from the cheapest sites (usually around $5 per 10k igg, but has gone up to around $7 as of late). The price on JSP seems to lag behind the websites i.e. site will drop to $5/10k, but sellers here still get around .08 - .1, which is around double the real money value they paid. I know not every big seller is like this, the way i've noticed is when the sellers "stock" AND price both directly relate to those websites (i know price will generally do that, as jsp is just a mini economy, but running out of stock when the cheap sites run out of stock seems suspect, though maybe they've just "sold out").
With that said, i've bought gold from 3-4 different sellers here on JSP, (some very big) and haven't had any trouble.