Is this argument bunk?

[mintacular]

I was talking to a hobby shop owner and he argued that one reason eBay $'s are lower is because they reflect the built-in "mistrust" buyers have buying online. By not being able to hold and see the card for yourself, the amount you might normally pay is less due to this uncertainty...Add in the issues with not knowing who are good eBay sellers/shipping concerns (legit or not) and you are going to get some lower sale prices.

So for example, if a 1958 EX Mantle sells for $200 on eBay this price reflects the buyer's (and underbidders) cautious attitude to the true "EX" nature of the card...

If you factor in shipping costs (mostly with lesser dollar cards), is this a decent argument for sellers at shops/shows to argue for charging higher prices, so long as they are in the same ball park as eBay prices?

I guess some of the merit of this argument weakens when you consider graded cards. The reasons I bring up this topic is that I met a guy at the flea market and he was griping about how he recently bought a lot of '69s on eBay and half of them were overgraded, etc. and how he didn't mind paying more from the dealer we were buying from, not to mention he doesn't pay shipping. Maybe there is room left for person-to-person selling of cardboard pictures of baseball players after all

Thanks for your opinion(s).