This is the favorite of my two 850Gs. A 600 dollar purchase in sound running and charging condition. I used it as a loaner for the family tours I was doing for a couple tours before I put new tires on it and checked out/repaired the charging system. It is smooth and shifts great. It now has about 47000 miles, about a third of those since I bought it. Batteries? a couple. Tires? It can use another set. Expenses? Used Honda R/R, and some cables, gaskets, and carb O rings.
Bikes aren't cheap, but the cheapest isn't always the best deal. Many will need tires and a battery though. The thing about non runners is that when you get them running, you won't know what you have. That said, GS are so robust that I basically expect the mechanicals to be solid.
Oh yeah... That was $600 and he rode it over and dropped it off from 90 miles away. Sight unseen. Came with a set of soft bags and that Hondaline locking trunk. It had a Windjammer - like fairing on it, but luckily, it had the headlight ears and bucket on it.
This was also $600 bucks delivered. It came with brand new BT45s on it. It had a bunch of rusty junk racks, case gaurds, and weird doo dads. This is after half a day of cleaning and polishing. It ran great, charged, and everything worked. Best deal I ever got. Around 2007 or 2008.
A $450 non runner would have to be pretty decent and whole for me to buy it. If it shows evidence of too many thumbed hands being used on it then I would have to pass.
This last bike, it turns out had been resurected by a friend of mine who buys and refurbs bikes as a hobby business. He rebuilds steam turbine engines for a living. I rode it over to show it to him and he wanted to buy it back. It needed nothing but the ugly fat slippery foam grips to be replaced, really.
At least with your G you don't need chain and sprockets. The shocks, in my personal experience are long lived. One thing people don't readily see is the cost of putting the carbs right if someone threw the airbox away. Yes, jet kits work, but they don't give them away. That and rusty shocks and forks.