I reckon you could use a normal black fibre glass style if you cut to the correct size - it just sits in the black cups - and the sleeve is a universal size.... may save you a few bob - !! - as a last resort if you cant find the official piece.
Cheers Candy Floss, only problem is we don't know the length needed. We did try last year with a fibreglass pole from an old pop up tent but it kept braking.