well I am personally newer to can than to speakers, here are my suggestions
I personally own a pair of magnepan MMG's which are amazing and do have sort of the Grado revelatory high end and mid range sound that grados are known for, in fact they sound really great with my grado blue cart. However these speakers are power hungry and require at least 200 watts of clean low distortion power to sound good, because they are 4ohm Oh yeah and they need a sub for bass more or less. I would also recommend Monitor audio silver series, or if you could get them used the GS-10, these have a similar wide frequency extension to grados from 40 up to about 43Khz and are an 8ohm speaker so they are easier to drive. I would also recommend amphion, which might be had for about 500 used, they use a tweeter that starts at 1200hz and goes up to 20,000hz without a cross over much like headphones, they also are 8ohm and never drop below 7ohm, but are like an 89db efficaincy. triangle electrostatique speakers are also very good, they have very revelatory high end and rock solid imaging and have many mini monitors to choose from as descent prices, and they have the right in front row sort of sound that grados have, but many of these do also create a great sense of space like grados. But really all of these speakers appropriateness is dependent on the system you have to put it in. I hope that helps