To understand what "contingency bidding" would mean, please refer to the poll part 1.
If AS offered contingency bidding, AS has indicated that they may plan to charge somewhat more for this service. For example, a snipe placed on contingency (i.e. a snipe that AS places only after first checking whether you've already one another, previous item) would carry a charge of 2% or 3% of your winning bid, instead of 1%.
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