How to bargain with someone on an atv?

Ok so a guy lent us his 150cc atv and told us to play with it today and let him know if we want two of them for $2000. We thought 2 atvs for $2000 thats a great deal! then I look online and new they are 1,200 with 3 yr warranty. the are taotao usa ata-150b... You can even find them for less. I want them really bad and it easier to go through a person then a dealer... How do I get him to lower the cost without l;osing the 4wheelers... Plus when we took it home the seat fell off of one of them.!!! We can't find it? omg... I hope he does not hold that against us... he kinda threw them onto us...