[Heathkit] SB 614 vs SB 610

[Art]

I am clearing out my shack and trying to get a ball park value for a 
Heathkit SB 614 Station Monitor
I find somewhat different prices for the 614 as with the 610.
Can anyone advise me of the differences and why a price difference?
Tnx & 73,
Art K5FNQ

-- 
What's that smell in this room? Didn't you notice it Brick?
Didn't you notice a powerful and obnoxious odor of mendacity
in this room?...There ain't nothin' more powerful than the odor
of mendacity...You can smell it. It smells like death.
Cat on a Hot Tin Roof - Big Daddy, Act 2.