Missing keycaps, dirty, banged up or not working seems to (recently) fetch about US$450.
Perfect condition with original box seems to go for up to US$950.
It's really going to depend on the condition, presentation and accessories.
Pretty darn good prices, though admittedly these are only recent "sold" listings on eBay and are very few in number so are a small sample size and thus may not be representative of it's quick sale value.
Wish I had three of them myself.