I would also be EXTREMELY picky about vendor selection. One large computer company, with a substantial consulting practice, once supplied a previous employer with four consultants. Of those, three were unequivocal disasters:

• One of them didn't know how to tee output to a file. Consequently, he kept trying to do Windows NT line printer dumps to a network printing facility that was actually a postscript-input filter on Unix for an otherwise-network-connected laser printer. If that last part doesn't make sense to you, it didn't make sense to us either; it was one of those "Why the H$@$ are you doing that for?" moments.
• The second one actually predated me by a couple months; it was a quick stint to write some administrative scripts for a Unix cluster, so that configuration changes made on one would be propagated. Apparently, nobody taught this particular programmer that path-substitution is a good way to hack poorly-written setuid scripts; there wasn't a single hard-coded path to anything called within them.
• The third one was ostensibly a C programmer in Unix. However, he insisted on editing everything on his Windows laptop; he then had to be trained on how to upload his files (!!) to the servers, and how to use a C-compiler from the commmand line. I have no idea how (or whether) his C code actually worked, but my experience as a sysadmin with him was that he was effectively clueless.

So, YMMV, but I would look for vendors who can supply individual consultants who can demonstrate a pattern of past successful deliveries of e-commerce consulting IN perl ON YOUR PLATFORM. Just because someone is a multi-billion-dollar company doesn't mean they don't have idiots working for them; statistically speaking, they should have n times as many idiots as a company n times smaller.

Spud Zeppelin * spud@spudzeppelin.com