Grado PS500 headphones are part of the Professional Series of Grado headphones, which sits above the Prestige series headphones such as the SR325. These headphones are simply fantastic, and I cannot recommend them enough for anyone who wants to enter the world of hi-fidelity music. I recently upgraded my hi-fi system and do not listen to music on my headphones anymore, so its time for them to find a new home! There is a defect that does not affect sound quality, comfort or functionality, but that I wanted to point out for transparency: The plastic ring that holds the left speaker broke and I had to fix it with superglue. I have used the headphones a fair bit since the repair and have not had a single problem. Frankly, it is hard to spot, and I had to use a super macro lens to be able to show it in the pictures (see last photo). I replaced both earpiece cushions with official Grado cushions, so they are barely used, hopefully that makes up for the repaired bits!
I don't have the original purchase price but I bought them new for around 800 euros. The price reflects the cosmetic imperfection due to the repair. However, you will get sound quality that far exceeds the price.
Review (french): https://www.diapasonmag.fr/diapason-dor-hi-fi/diapason-dor-2012-casque-grado-ps-500-4528.html