Below 200 USD is kind of hard to negotiate, there are amps out there such as the Headsix that I do recommend.
But my personal experience with my EW9s is that i really dont use an amp with them simply because it is easier for transportable purposes (Ipod 5.5). However, I have had a great experience using ESW9 and C2M (Corda2Move).
I use a Minibox-E+ ($184 shipped) with my EM9D (the more open version of the EM9R) and they work pretty well. As for whether or not it's worth it? Hmm... well, it does help bring things forward that I never noticed before but $184 is a big chunk of change considering I only paid $60 for the EM9D used, haha.