Correct. It’s the same level of security (read: inconvenience) that prevents hotlinking.
With the 403 in this case, you have to hope that either:
That’s enough to turn off a possible bidder, that maybe hits refresh once (and doesn’t think to simple hit enter or the go button). A potential bidder could see the error as a problem with the script that they were considering bidding on and lose interest in the auction (good reason for the seller to find a new ‘demo’ site).
The seller isn’t a jerk that changes the link to “Copy & paste this URL in your browser.” Then you’re pretty much screwed, unless you want to dedicate part of your homepage to calling the seller a jackass and linking the person to a place where he/she can get the script for free.
That’s why I’d take the more fun route of redirecting to porn or beastiality … let them refresh all they want. And in that case (unless he goes plain text instead of link), he’ll surely get several ebay complaints about it.
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