According to Tractordata.com..they were build between 2003-2008.Not like cars tho,condition is everything.Stored inside?,paint faded,maintainence performed.Ball park $10,000-$13,000.
I have used a B7800,decent machine.
Just as it was stated above. The number of hours and the maintenance, general condition matter more then the year it was made. I own a B7800 (370hrs +/-) that was made in 2004 and it is a very good machine.
I bought a new B7800 in 2007. The serial number is 69,857. I'm not sure what year it is. It could have been a left over from the previous year. What year it is doesn't matter on tractors. Its the hours and condition that matters. My B7800 is a rough and tough little tractor.