Just bought a Dynavector 17D2 for 160$

Not the mk 2.

It is barely used is it a good buy and good cartridge
If it works and sounds good to you, then yes, it was a good
buy. IMHO, I would have bought it for $160 as long as it was
in decent shape and worked. It's an excellent cartridge.
The seller just informed me that this actualy is the mk2 version.

That makes it a seriously good buy doesnt it?
Yep a very good buy. I haven't bought or sold used cartridges and don't know what the typical mark downs would normally occur, but I know the price you paid on that cart. represents a much much greater mark down than %50.
Dynavectors last. I have a 29 year old Dynavector Ruby 23 which is great.
The body is worth about $250 even if it needs a retip.
So yes you got a good deal.
Does anyone know what it cost new?

And has anyone here heard it?
A brand new Dynavector DV-17D3 (current model) retails for roughly $1,100.
When your cartridge was new; it retailed for $795. There
have been four iterations since then(over 13 years),
including new/improved models and various changes(ie:
compliance, output, etc.). If it sounds good to you........
You seem to have gotten a great deal. But I'd also be sure to get the cart checked out.

Get an idea of how the suspension and tip are holding up.

Even with this great deal, you may be faced with some repair and upkeep costs. Well worth it based on the reputation of this cart and what you paid.