Make an offer. Price negotiable.
Just to be clear, here. You're asking 150USD per PSU and not for the lot?
The PSU has a Poor OEM so 150$ sound only a little low for all of them, while 150$ per is way too high (can get EVGA for 100$ which are superb).
Yes per unit but that includes shipping from Canada. I felt that was a fair price to start, sorry if I'm way off base here. Not sure of its resale value and PSU's seem to be more expensive in Canada.
I don't mean to "push you off base", you'll just notice, especially for non high quality OEM psu, you will get little interest and very low offers. As far as used hardware go, its often 50% off retail price just for the fact its second hand. (And you typically lose fully or partially the warranty.)
Most educated buyer will probably stick to EVGA, Seasonic PSU or Superflower, Seasonic, etc as OEM. Thermaltake are typically in the "usually decent" category.
For learning more about your PSU;
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story5&reid=243TLDR they are expensive, average PSU, not horrible but not particularly good either. The biggest problem with this one is its being sold at the same price as premium, top notch PSU.
It should probably be 170$ brand new. As a buyer myself, for a used one i'd put up 50-60$, if i badly needed a cheap PSU. But i would probably not use it much or for long, since i like to keep my miners running on cleanest power.