Hi Alison,I dont' know much about the exact price but here is another website you may fine interesting :
http://members.tripod.com/~Lehart
Gilles Lehart is a Breton flute maker, but who also makes Bombardes and Biniou Khoz. I think his prices for irish flutes in D are about 4000 FF (about 400 sterling) for keyless flutes, then any added key must be about 45 sterlings. I know his flutes are very good, so I guess 999 pounds as you said is a bit too much , especially for second hand. you can find other websites about irish flutes through : www.ceolas.org
Bye
Rob