Five "Golden Rules" of HiFi?

Wow how interesting!!!!!

(1) If one waits for a product that one deems relevant for one's system...waiting for that product to meet a price (low/used) point but will not benefit you in the long run. Buy it, enjoy. Life's short!
(2) Buy what you perceive is in your best interests. Whether it's used or not...waiting could be forever, buying sooner will be beneficial for your own benefit plus you'll have more chance to listen to great music reproduced better in your own home!
(3) Buy lots of music!
(4) Read a lot. Listen a lot. Make your own decisions based upon your own experience!

I forgot... I have one more...
(5) Learn how to listen, learn what to listen for. (Maybe the most important of all).

Biomimetic the trouble with headphones (for me and I assume others as well) is that you can't get a soundstage. The performers aren't performing in front of you, they are in your head!  While this may sound like a good thing, I can't get used to it as I don't find it natural. 

OP-

all of your points taken except buying 2nd hand speakers. Nothing wrong w/ this practice so long as you trust the seller.