I believe what is happening to you is this: Someone sees an item listed at vendor price of 2k, he really wants it so he bids 1,000,000. You see the item but it still just shows 2k as the current price. You bid and use the default amount that pops up of say 2.2k, his bid of 1m is still more, and you will get that message and the listed bid goes up to the 2.2k. You can keep bidding it up with default bid/random prices and will never beat him until it gets to over 1m.
If you do a high starting bid like that and they never outbid you, you get refunded the gold, i.e. you bid 1m, they bid it up to 200k, you get 800k back.
Lots of items get put up for vendor/low bids with no buyouts. A lot will wait until the timer gets to <1 minute to bid on them. To try and avoid getting 'sniped' try using odd amounts, for instance they will usually bid in even amounts like 250k, so a bid of 251k can secure it, or bid a large amount that you feel comfortable paying in full, just in case they do bid you up that far.