I've put some of my stuff up for auction before at a discount and it's been bid up to three times higher than what I sell for on the buy it now format, both were in my shop at the same time and in the same category, I stop doing that now as I want people happy with their purchases and not feeling done even if it was their fault for bidding it higher than its usual price.
People can get carried away when bidding if they both want something also there's factors like setting a high bid, doing that one extra bid that becomes three and of course unscrupulous shilling by the seller.
Also there's the sellers feedback, postage times, returns policies and how their page looks that can justify paying a touch more for peace of mind.
