When talking open backs I think of AKG. I find they offer lots for the money. In your ball park the K702 for around $210 on Amazon.
There is also the K701 for around $220 and the Quincy Jones version Q701 for $240.
Grado's also sound great. The SR225e is $200.
AKG's are more available in stores while the Grado's are a boutique headphone. They are available direct form Grado with free shipping in the US for $200. Grado's are pretty much the standard and always well reviewed and many drool over Grado's jsut because they are Grado's.
After reading some reviews here is the lowdown. The Grado's sound great with a bit more bass. But the AKG has tighter bass, more overall clarity, and are much better balanced for a full range...