Grinding your own, as you know, will allow you so make the necessary grind adjustments to get the best out of your machine.
i'll be glad to take a look over at Amazon, but to be honest, you may be better off, both in terms of the quality of the grinder and, surprisingly, the price, going to a good espresso equipment site. I have several that I use, and i'll send links if need be.
Be forewarned, I'll probably recommend something in the $200-$250 range for two reasons...a better grinder, and a grinder that will work for you down the road if/when you upgrade your machine. Remember, second only to the beans, the grinder is the most important piece of equipment.
I'm open to any recommendations of course. The price range you cite will fit my budget just fine too.