It will cost whatever you want it to cost, if you're patient enough to scrounge up the parts. In other words, you can trade time for money. What's your budget?

If you really want to tinker, you can do it. You just need time and patience, and I highly recommend that you do it. You have lots of us mechanics here to help you whenever you get into trouble.

If you just want it to work, buy a replacement bike. The nice thing is that you already have more than one bike, so when you render a bike unridable for a while, you can still ride.