Anyone had to have viewfinder or AF problems fixed?

Can you send it to Sony to get a quote for the repair. It might be worth the $120+ to know if there are any more potential problems.

Then it comes down to your risk tolerance and the cost of repairing the camera. Is $500-$600* (or however much it costs) for the repair worth it, or do you spend the extra for a new body and for peace of mind that you wont have any issues later on.

Only you can answer that question for yourself

* that figure is just an example. I dont know how much it would cost for a new view finder or AF repair/replacement