I'm surprised it was that cheap. My son did not properly latch the bunk escape window once. On the way home it blew off the side of the camper. No damage to the frame but the window itself was gone. I think it was around $320 just to replace the window without the frame. And that was me installing it myself.
I would spend the money and make the proper repair before I tried to cover it with a patch plate and a knob from home depot. I did not notice what kind of rig you have but with multiple slides and "remotes" I'm sure it was not cheap. The joy of saving $150 will not last long, looking at your patch plate repair on a otherwise pristine rig will stay with you forever.