One of the clues to this "enterprise" that I've seen is that "User B, C"
etc. will generally be "New" E-bayers (zero bids) with free e-mail accounts.
I have seen it often on items that have not received any bids in the first
few days. 
I agree with David C. & Chuck, just bid what you're willing to pay and hope
for the best. That's how I bid.
Herby
64 MK II Sprite - HRBYTOY (under construction/de-construction)
billh@aaai.com
www.herbytoys.com
User "A" also has
  friends User "B" and "C" who bid on a product to 
  drive up the price with no intention of purchasing
  it. If it doesn't sell, 
///
///  (If they are dupes, this trailer may also catch them.)
 
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