They originally sold for around $500 in Japan. They later sold a Kit that went for about $350, and a guy on Ebay is listing them regularly for $600+ right now.
The early ones came with a plastic guncase and were numbered on the buttplate. The airsofts are also of higher demand and a bit rarer. At one time they sold for over $1,000 on eBay, but they have dropped as a result of the kit version. I think a fair price for the early version would be around $700-$800 unless it was one of the very first ones. The early ones also purposely misspelled the "Steyr Mannlicher" engraving by switching the 'E's and the 'A's.
The PFC cap version is the one I have and it is extremely impressive because of the weight, and craftsmanship that went into it. It truly feels like a real weapon. They might not be accurate, but they feel and look real.
In the end it is worth what someone is willing to pay for it, but I hope some background on it helps.
Andy