I think ebay sellers these days are too dishonest to honour the notion of selling with an auction. Basically, we all have an idea on our minds how much we want to sell something, especially for expensive/rare cards. So instead of setting up a Buy It Now item say for $100, they start it at $0.99 and try to guide it to an amount that they feel comfortable selling with.
I can understand how someone would feel when you see the potential of parting with that card for $10 instead of the $100 that you had in mind. But I do not support the idea of shill bidding. I believe if you don't want something to go for cheap, either set up a BIN or don't sell it on eBay at all. There will always be a risk of selling low sometimes in an auction. But it also attracts more buyers due to its low starting price.
Nowadays, I track items' prices on ebay and I noticed cards that I have seemingly lost to another bidder, being re-listed straight away. I hate those people, because they are doing it so blatantly. I have seen some guy re-list the same guy 4-5 times.