I think a lot of bidders get caught up in the "heat of battle" with those 1cent auctions without approaching it objectively as to actual worth or considering the financial outlay they are in for.
Plus labour costs are grossly undervalued in pinball restoration.
Then the issue will be the amount of $$ than needs to be spent to restore the machine. Unless they are "Holy Grails", then it is best to stay out of the bidding wars.