Right, the problem always is when you can't buy a plane with the gear you want. After flying in Av Shiloh's Comanche for a few years (actually the first time I flew it with the G-600, I knew I would never again own and operate a plane without this technology, it would be negligent. In order to buy a light twin with the equipment in it would have cost $800,000+, instead I have about 1/10 of that invested in a plane that does the same job by taking an excellent plane with an older panel and putting a new panel in it. You can't get into a glass panel twin cheaper than I got in mine, can't do it because there are none for sale. People tried to, but guess what? They couldn't because I wouldn't sell, now I won't sell for less than $250k again, don't want or need to, I'll have an amphib soon enough.
But what you have to realize is that the younger generation is learning to fly with glass panels from hour-one. Anything you own has to be upgraded to account for that. An older 310 like you have has a lot of utility. For now. On the other hand, the pool of people that are willing to buy an older 310 without 5 video screens becomes smaller every day. The best we can do is to form Captain Henning's Aircraft Salvage, LLC. You bid for them, I'll haul them home and drill out the rivets so we can eBay the parts. Sad, but that's how it is.