I say, it's your couch and your home, do whatever pleases you
Having said that, aqua (turquoise?) sounds kinda 70's. My parents had a turquoise leather couch around then.
If you're not sure you made the right decision, and you're second-guessing it, chances are you'd be wise to listen to that "little voice" and cancel the order while you're re-thinking. As you say, it's a very expensive mistake, and reupholstering a couch is about as expensive as buying a new one.
Generally speaking, it's often wise to stick to classic colors in your major pieces, and freshen it up by changing out the accent colors as the mood strikes you --- artwork, rugs, throw pillows, curtains, etc.
Some different stuff:
http://www.thegoodtimber.com/FinalPics/leathCouch1.jpg
http://k53.pbase.com/o6/76/602476/1/...rciesun2sm.jpg
http://www.bigfatmoney.com/images/couch.jpg (broken link)
http://www.mysanantonio.com/salife/gardening/stories/D_IMAGE.11432118fbd.93.88.fa.d0.189d86445.jpg (broken link)