Where is the 2000 sales figure from?
Sales ranks look pretty good on all pages.
At £20 new it's not cheap, and 2000 sales already at that price doesn't seem bad at all. But I wonder whether the optimum price may have been a bit lower. Maybe £10 to £15.
Anyone can write a book on any subject they like and charge whatever they like. It's up to others whether they buy or not.
I find it annoying that some people think work should be given away free. Or that writing is not real work.