If anyone is particularly desperate I believe the lower price is still available from eg the German site until the end of the day today.
It isn’t unusual to offer a perk (whether that be free extra content or a discount) to people pre-ordering a new product on faith but odd that it cuts off so far before actual reviews are out... the advantage to them is it gives some solid figures on demand, ensures they aren’t significantly over or under supplying. It generates buzz and publicity, all those early owners can rave about your product when they get it and spur further sales, and it locks down orders In advance... If for example oculus’ new headset comes out and just for the sake of argument was very similar spec wise, chances are a good number wouldn’t give up their pre-order discount to switch. So you can see why it can be beneficial even if it eats into profit.
That doesn’t however mean £525 is a sustainable price for them longer term. I must admit I’m surprised by how deep the pre-order discount is (was) though.
That said anyone pre-ordering now is still doing so on a leap and a prayer so it would have been nice for the discount to run longer but perhaps they’ve calculated that they have hit the total of what they can supply for the first wave, or max budget for marketing spend which is what the pre-order discount effectively is. Who knows, but HP aren’t stupid so I’m sure it’s all been costed and carefully strategised.
If you look at it objectively, you are getting a G1 with (one would assume given the specs) at least equal cost if not higher cost display, two extra tracking cameras, more complex higher quality lenses, and a significantly better audio solution. The G1 sells for £600... it seems unlikely they could offer all that extra stuff for £75 less in not much more than a year after launch of the G1.