I am far from an expert here but I've seen a response to this sort of question before and have experienced it myself.
AS puts in your bid and it works just as any other eBay proxy bid works...it will increment it only over the highest bid cast.
So, for example, if the widget your bidding on is at $2 and you've put in a $50 snipe...and the bidding never goes higher than $2, then you would get it for $2.25 (or whatever the increment amount was). If that original bidder had a proxy bid in of say, $25, then you would get it for $25.25. but it could also reach your limit if a bidding war works its way up that high. Now if it goes beyond that $50, then of course you won't get it.
HOWEVER, keep in mind that if the original bidder's proxy (or any bid placed before yours) was also for $50...they would win it as their bid was cast before yours. Highest bid always wins...unless there's a tie, then it goes to the earlier bidder. (A risk I'm willing to take after placing my snipe for my highest possible dollar)
Good luck!
WarriorNun
"If you can't be a good example, then you'll just have to be a horrible warning"