Maybe in the $400.00 to $550.00 range.
This model was made between 1984 & 1987 with original retail of $575.00. That is about $1250.00 in today's dollars.
There are a few sold T-60’s on eBay, so that should give you some idea.
https://www.ebay.com/sch/i.html?_odkw=Harman+Kardon+T60C+turntable&_sop=16&_fspt=1&_mPrRngCbx=1&LH_Complete=1&LH_Sold=1&_osacat=0&_from=R40&_trksid=m570.l1313&_nkw=Harman+Kardon+T60+turntable&_sacat=0
Here is one:
http://www.usaudiomart.com/details/649252763-harman-kardon-t65c-turntable/
This model was made between 1984 & 1987 with original retail of $575.00. That is about $1250.00 in today's dollars.
There are a few sold T-60’s on eBay, so that should give you some idea.
https://www.ebay.com/sch/i.html?_odkw=Harman+Kardon+T60C+turntable&_sop=16&_fspt=1&_mPrRngCbx=1&LH_Complete=1&LH_Sold=1&_osacat=0&_from=R40&_trksid=m570.l1313&_nkw=Harman+Kardon+T60+turntable&_sacat=0
Here is one:
http://www.usaudiomart.com/details/649252763-harman-kardon-t65c-turntable/