My remote setup (ok, it's only 50m away, but I still never visit it!) has only had one unrecoverable issue in its 5 years.
That was the untimely demise of the Dome shutter battery which I had neglected to swap out routinely and caused the dome to remain open which could have been very nasty indeed. As it was it caused me to leave the comfort of my house to venture out into a brisk Qld winters evening
Like all problems, remote observatories can be made so much easier with a liberal application of money. The cheapest 'turn-key' solution is probably a fully automated 2.3m Sirius dome, but you won't be seeing much change from 20k once you have put it on a slab
The good news is that the dome will last forever and can easily be taken down and moved if need be. It was certainly a big factor for me as I don't have a great track record of staying in the same place for too many years - too much of the wanderlust still in me!
And something that hasn't already been mentioned - I have found that critters tend to take over the observatory after a few months unvisited. In my case the corrector plate on the SCT has taken a serious battering from various bug juices and I had a nice colony of red backs settle in with many thousand ants who just loved the warmth of the electronics...