Can you not find a retailer that stocks any Grado near where you are? Even if you cant hear the 325s, would be useful to try a lesser pair if possible. Whilst not sonically the same, there is definitely a Grado "sound" that some love, some dont. Also, the style and fit is similar between models. $300 is a lot to spend totally blind.
PS- avoid listening to anything higher up the range- that will just result in a bigger dent in your wallet.