I think the stones he eBays are stones he feels he will get more money on eBay for than if he listed at his site.... on average.
Browsing his site seems to confirm this.
Stones that meet his listing standards can be had for listing price or less, but usually sell fast (often quite a bit less than eBay price), more often you find equal or better (rated) stones that are quite a bit larger for similar or slightly more available.
A bit more that I know about him.
His STARTING ebay price is what he wants for the stone. Everything else is gravy for him. I get Second chances any time I bid opening bid on his auctions. You figure, ebay, paypal, shipping all taking a cut. He's seeing what, 75% of that price. I'd say if you can make heads or tails of his webpage, it's by far the best way to get a stone from him. There's a reason the eBay stones aren't listed individually, while he has listed some $10 Iyo's individually on his website. He's putting less effort into these stones because they are worth less to him. I THINK that's what that email you posted was trying to convey. The reason he lists the eBay stones for what he does is because he's not testing them much, grading them, sorting out cracks or looking very hard for detrimental inclusions. He slaps them with some steel, see's that they're "Good enough" to list under the approximate ratings his eBay auctions give, then ships them out. When you're asking him to handpick a stone he see's maybe $30-50 of the cost of not considering what the stone actually costs him (my guess is not very much), you're asking a lot of the guy. If he was going to test them and find what you're asking for, he'd do that and list it on his site for $150.
Cordiallity has a tendancy to get lost in translation.