I never really looked at linkshare merchandiser for data feeds since they initially charged for access. I see now that they have dropped it as long as you have been an affiliate for three months and generate over 50 sales.
I don't have a problem clearing that now but stuff happens, has anybody who is using it ever fallen below the threshold and gotten hit with the $250 fee?
They set up an FTP account for you, and secure access to a single IP address that you name (a bit excessive, but that's Linkshare). Or at least that was the procedure 4 years ago. I paid the $250 up front.
So there is that setup cost to them, but the $250 is most likely to keep out the tire-kickers.
I doubt very much that they have the infrastructure in place to perform checks and ensure that you've been keeping up with required sales.