My microwave recently blew the fuse. They really didn't make it easy to replace the fuse -- I got the manual online and it didn't say much of anything about it. The outer shell of the microwave (sides and top) was secured with tamper-proof torx fasteners, but the bit to remove those is a couple of bucks, or just use a pair of vise-grips. I felt comfortable removing the shell because I am aware that, while there is a high-voltage capacitor inside, they make it very clear where it is and make even more layers to remove to get to it.
Sure enough, with the shell off, there was an area that was clearly marked as the dangerous part, and a piece marked as the fuse right where the power cord comes in. It even had a little diagram that said what to replace it with. $2 at the local hardware store, and about 5 minutes of actual work to get the shell on and off.
Even without the benefit of saving $50-100 over buying a replacement microwave, this repair paid for itself just in my time. It is faster and less hassle to take the damn thing apart and fix it than either going all the way to the appliance store and buying new, or finding one used on craigslist, and then having to haul it home on bike.
It is my opinion that they make it look hard/scary to replace the fuse just so that people will buy a new one instead of replacing the $2 part. Sure, you could kill yourself on the capacitor if you are a complete bozo and do something completely stupid, but IMO replacing the fuse isn't inherently dangerous, even when removing the cover. Of course, unplug first and take responsibility for any choices to proceed with repair.