SR60s have to be near the top of any list of budget headphones. They get universal praise by anyone who has listened to them. That being said, if I were in your position, I would listen to some Sennheiser HD201s. About 6 months ago, I heard some and was floored by their performance. They are not HD580 or HD600 good, but IMO, they are VERY close in performance to the SR60s but can be had for 20-25.00. I would buy them and set a 100.00 aside for a future headphone amp purchase.
Another way to go but its a bit out of your current price range is some in-ear monitors like Etymotics ER-6, Shure E2C, and the Ultimate Ears Super.Fi 3. Ety's absolutely own the mid-high end portion this market, but Shures have put themselves in a position to be competitive and the E4C being particularly good but way out of your price range. The E2C compromises a bit of midrange "openness" for lack of a better term, but is good. Under 100.00, the Super.fi 3 is my choice.
I don't have a lot of experience with Sony cans, but have heard everything from glowing reviews to awful reviews of just about everyone of their high end models. I tend to believe the glowing reviews more than the trash ones based on opinions from those people I trust.
As a side note, if you are into rap, rock, or other in your face styles of music, the AKG K 26 P is cheap, sounds pretty good, and has outstanding bass response.
