Why are they so high priced?

On the numista page it says that the bullion value is ~$4, but most people are selling it for over 100 dollars. The lowest priced one I can find is for $60, and it’s in bad condition. Is there any reason why the price is so high?

Look at the mintages and consider they were released into circulation.  Supply and demand drives the market.

Numismatic value has very little relation to material value. If you want to buy metal buy metal not coins, you will most often have way less premium.

I didn’t want to buy it for the silver, I just wanted to buy it because it’s the only circulating 20 cent coin from the US

Pluto2181930

I just wanted to buy it because it’s the only circulating 20 cent coin from the US

That's exactly why they're so expensive, a short lived type, plus an odd denomination. That makes for a lot of demand for them, which explains why the price is high despite the coins being pretty easy to find.