Why are you going to buy a pair of new Grado SR325i headphones that will probably be "bested" as soon as your modifications are complete on your SR60 model? Or, do you plan on attacking the SR325i as soon as the SR60s are done being modified? If you're jumping up to the SR325i headphones and plan to keep them stock, you should also take into consideration that you're within a small range of money by going to the RS2i, if you get a used pair. If you get a chance, please do demo a pair of SR325i before making the leap. They are a different type of headphone - and do behave a bit differently (weight, sound on the low end - as indicated by Bilavideo).
With that being said, I have a pair of SR325 (non "i") version that I picked up used. The price was right, but I would never see myself buying this model at the new price.