Like it or loathe it, (I'm in the latter) shilling is a fact of auctions anywhere and everywhere.. It can be out ruled or even made illegal but people will still try it on if gives the chance of greater returns. its been going on for as long as auctions and it likely always will.
Sometimes its underhanded other times its blazen. in housing auctions in my part of the world the auctioneer places owners bids if the price isn't where the the owner wants it and its legal.
However at the end of the day, no buyer has to meet a shills bid, so as long as you only bid what you were willing to pay, you never pay more than you budget (though may pay more than was necessary) So if something ever does sell at these prices there was at least one keen, legitimate, wiling buyer
Truth be told, if I was made of money I'd pay whatever I had for these and would drop a huge bid for spawn sketch covers, but alas I'm not so my budget is usually $100 and I've got no chance.