What's the market these days for NOS 70's/80's cartridges and/or tonearms?

The difference between audiogon and better platforms like ebay and US Audio Mart is the listing fee. Nobody charge listing fee, except audiogon!

On Ebay you pay fee only if your listing is sold.

On US Audio Mart you don’t pay anything at all in any situation even if you sold your items. It’s free platform and extremely popular.

Another new platform is Reverb.

But Audiogon will charge their free just for listing, they want you to pay them even if you item remains unsold (and most likely it will be unsold for a long time). 
Auction is very bad idea for beginner if you don’t have followers and feedbacks, your item can be sold with very little interest for very low price if it will be an auction.

@rauliruegas;@chakster

Thanks so much you guys.  I guess because I have no feedback (never been a buyer or seller here, since almost all my sales have been private party or dealer sales and/or trades), and I had thought Agon buyers are a bit picky about the lack of sales history.  But perhaps I should give some listings a try, as you suggest.

I don't have a lot of items, but do have a few I believe are desirable, e.g., Shure V15 Type 4, NOS; Stanton 681EEE MKII, NOS; SME3009R, NOS, unopened; 1957 TD124 (first year production, likely Sept S/N) from estate sale (it came with a Rek-O-Cut 120, and everything functioned fine).  Other items are just vintage HiFi equipment, of which I purchased new in mid-late 70's, that I previously had an nostalgic attachment to, but fortunately for which I kept all boxes and manual - - like Pioneer Spec 1 preamp, JBL4311WXA, Phase Linear 400, and, most recently I decided to sell my Herron VTPH-2A phono pre (only 40 hrs on it, so it should go quickly).  Again, I'm not trying to elicit buyers in any respect by identifying what particular items I'm interested in discovering the market for purposes of listing appropriately in accordance with, especially, Agon standards, etc.  

Even if you don't have any feedback history you can still make fair prices (especially for NOS items, for used items grading must be very accurate, it's better to under grade than over grade) and build your reputation. With paypal your buyers are fully protected with paypal buyers protection (they can return everything for full refund if they are not happy with condition).  

@chakster

Thank you for the kind and informative response guiding me through the various online seller/buyer options, plus the other advice relative to selling - very helpful!

you're welcome :)