When everything it working, an aviation GPS that is used for IFR approaches is not any more accurate than a consumer grade GPS. But the aviation GPS does more checking to determine if the navigation information can be trusted.

No, not really.

This doesn't increase the initial cost, but it is a pain to constantly be updating the GPS database.

This is the big one!

This is the key point. I own 25% of a plane and occasionally get comments about how it must be nice to be rich. But my non-aviation expenses are significantly less than anyone else I work with. I value having a plane more than I value having a nice car, house, being able to eat out frequently, etc.

Not many of the new 406 ELTs contain a GPS receiver. Some are able to accept GPS information from a separate GPS receiver, but they are more expensive and installation is also more expensive. When I had a 406 ELT installed, I did not get the GPS option. The shop that did the work, said that only about 10% of his customers have gone for the GPS option.

You are probably looking at hand held beacons that you manually activate. An ELT that mounts in your aircraft costs significantly more because it has G sensors to detect a crash and because it is a certified part. Also, installation is not cheap. It cost me $1500 to put one in my C-172. $1000 for the ELT and $500 for labor.