I would think about how you are going to use the room. Are you really going to be sitting and listening intensely and critically? Most likely not - so get some exciting active speakers that are well below whatever budget you have in mind because honestly you want to be focused on the workout not whether or not the sweet spot is just right. The Klipsch The Fives come to mind but I am sure there are others as well. You'll want something you can just kick on when you're ready to get moving and then easily disengage from when you are done.