I don't think that $800.00 is all that great of a price for a year 2000 commemorative. I have seen them listed for below that amount. For some reason, collectors never really 'took' to the 2k model. Earl had them listed on his website for quite somtime under the 'specials' section, at a reduced cost. From a collector's point of view, it looks like the 2k model really won't appreciate much. If you do not already have a standard production P99, I would suggest spending your extra funds on that over the 2k model (just my two cents though).
Like the old saying, it's worth whatever somebody will pay. I passed on a Y2K in .40 more than once. Just wasn't worth the premium to me especially since I'm not a collector of unfired pieces. The ones I have seen have all been well below $800 though.
The LaChase is sorta interesting to me.... Here is one that has been shot, and the guy has relisted this thing at least 5 times... maybe he's willing to work with somebody that really wants it. You can even see the fabric in the case is a little oily, so... maybe he has "room".