“We are playing for keeps” typically signals the reserve has been met and the house will sell to the highest bidder.
“Vendor bid” is used as an offer from the vendor. Vendor bids are used at the start of an auction if no other offers are presented, or after a slow down to rebuild interest.
“I’m confident the property will sell at auction today” usually means one of two things. Either the reserve has been met, or a lucrative offer has been presented before the auction with the potential buyers in attendance.
“Last chance” The house will be passed in if the reserve hasn’t been met, or will sell if it has.
“I will accept raises of $1000” bidding has slowed and the reserve has been met or isn’t far off.
“There’s real value here” Interest is low and the auctioneer needs to induce bids.
“This property will be sold today”, a regularly used ploy to try and create bids when a reserve has not been met; however, it could also mean that the reserve has been and that the house is on the market.