OBO

Acronym for "or best offer" which indicates that the seller is willing to negotiate. If you offered $10 for a vehicle and you were the only one who made an offer, technically your offer is the best. However most sellers understand "$3000 obo" as meaning "about $3000, maybe less." Some think it means "I'll sell it for $3000; but if someone offers $4000, I will take that instead."