Grados and Sennheiser HD202s (Score 1)

I can vouch for both the Grado's (SR60's in my case) and the Sennheiser HD 202s. I bough both on the recommendations of others and have found the Grado's to be the purest sounding (with no isolation) and reasonably flat with enough isolation to keep out the constant discussions going on around me in my workplace.
Both are IMHO great value for money.

The Grados sound best on my diy-upgraded iRiver H320 (CF drive, new battery, Rockbox) - the quality is noticeably better than when I used them on my iPhone 4. Alas, same can be said for my old iMac G5 (smooth Burr-brown audio) vs. my new Macbook Air.

In the end, buy to your budget - there's some great headphones out there for a reasonable price.