You can thank cryptocurrency miners for that. I am able to sell my graphics card used at a profit in the current market because cryptocurrency miners keep buying shipments of graphics cards. Availability is atrocious in addition to price. Just wait until NVIDIA comes out with the new GTX-series of graphics cards. We aren't sure yet what architecture they will be built on, it's either Volta or Ampere. We know very little about Ampere, but to give you an idea of how powerful Volta is, the Volta-based Titan V beats a GTX 1080 Ti overclocked to about max frequency, something like 2500 MHz. Overclocking that far requires liquid nitrogen cooling. So at stock speeds, the Titan V murders the extreme-overclocked 1080 Ti. However, a new one is something like $3000. Make sure to get your order in as soon as the new GTX cards release.
Speaking of the GTX 1080 Ti, new and used cards are now all above $1000.

I have seen new GTX 1080 Tis for $1400-$1700 on eBay. These retailed at $650-$750 before this stupid mining craze happened. My GTX 1070 was purchased new for $400 including tax. I am now in the process of selling it for $450. I could very easily try to get $550-$700 for it as that is the current price, but I decided to take the $50.
Anyways, definitely hang in there and upgrade what you can. These are dark times in the world of PC building.
PC Specs: AMD Ryzen 7 2700X @4.225 GHz, AsRock X470 Taichi Ultimate, 16 GB Corsair Vengeance DDR4 @3200 MHz, and an EVGA GTX 1080 FTW Edition