Ritchie Bros. rules are very clear from the outset. They are no reserve period. They even state in their buyers catalog about having other people bid on your items. They will prosecute you. Ritchie Bros. thrives in a bad economy because there are still people/contractors with money to spend. Dave Ritchie took about a 4 year cruise and it only cost him about $40,000,000. Sold the yacht he paid $100,000,000+ for at an unreserved auction and it only brought $62,000,000. I don't think he has too many money problems but commend him on selling it unreserved. Every Ritchie Bros. auction brings in $15 to $50 million in sales and sometimes more.
A lot of farm auctions you have no idea and the so called rules are changed to suit whoever. I've seen auctioneers yell sold almost instantly before anyone else even had a chance to get their hand up or shout out. Most likely buying it for themselves.