Well done, I think that is a bargain wherever the frame was made! I'll be interested to hear what the serial number is when you get it.
I think the difference in the prices you quoted is mainly down to the SID forks, which used to be fearsomely expensive. I happen to have a copy of the US prices of the 1998 range that I printed out on 3 February 1998. This shows that they still had the 'Custom Pro Series' and 'custom elite series' concepts, and the basic prices with STX-RC and rigid forks were Elite - Erzulie $630, Pro - Hoodoo (Reynolds 525) $924, Wanga (Reynolds 631) $1,074 and Bizango (Reynolds 853) $1,274. But if you had a Hoodoo with STX-RC and an SID, it would be $1,579.
There is no sign in the price list of whether or not the frames for the 98 range were still made in the USA. The Bizango frame was $849 and the Hoodoo $499, which maybe suggests that they were, but then a Reynolds 525 frame doesn't come all that cheap anyway and you would have thought that if they were, they would have said so perhaps?
I have no evidence that any frames were built in Chico after the end of 1996 when Jeff Lindsay left, although the factory definitely stayed open under A-Pro's sole ownership (they were joint owners before). There was significant bad feeling in Chico, so no doubt some workers lost their jobs either then or later. All the 97 Kona Hots and Kus I know of had 96 serial numbers, ditto 97 Bizangos, so one possibility is that they finished all their 97 model year contracts by the end of 96 and then sacked the welders and carried on with just assembly work. I don't know that, but it seems a possibility.
We don't know much here about the 1998 range as I'm pretty sure it was never imported to the UK. As late as October 1998, the prices quoted for VooDoo standard builds in MBR were the 97 prices, and I have never seen a Reynolds 525 Hoodoo. The trouble was that the Custom Pro prices were off the chart, so they were hardly likely to sell many bikes other than Erzulies. Their price for building an XT groupset onto a frame was £1,070, compared to Merlin Cycles £565. Merlin's price included their excellent hand-built wheels with XT hubs built into 217 rims with db spokes. And an (also excellent) Rock Lobster 853 frame was £299, whereas a Bizango frame was £699, so why would you go down the VooDoo route? Answer - not many did.