find replacement optical drives for iMac 2007

You can get them here http://www.allpartsmac.com/IMac-Intel_c376.htm

But, if I may suggest, consider replacing your optical drive instead with an SSD. The slot loading super drives are susceptible to failure while being boxed in with all of the iMacs internal heat not to mention the vertical orientation. You can leave your hard drive in place for storage, have a lightning fast boot and app drive and have an external optical drive that will last much longer. Win, win, win.

I suggest you get a 3rd party external optical drive so you can take it with you when you upgrade to a new iMac with won't have a built in optical drive. I got mine from otherworldcomputing.com: External DVD/CD Solutions. I recommend getting a drawer loading model rather than a slot loading model.