I know just the fellow for you. He's called Stuart Case and he sold me my RAF flying suit ( they're better than the american ones as they have kneeboards and more pockets than anyone could ever use) It was only about £55 or something because its second hand but its in good condition. He should be able to do you a good price and he seemed to have lots of flying suits when I went there.
His website is :
www.flightcaseinternational.co.uk but it wont have all his stuff there so I recommend you phone him, the number should be somewhere on the site, or e mail him.