They come up once in a while on Fleabay, the OE surlast covers.
Just make sure it's for a X2 with a tower and not a MS 200.
They are advertised as fitting an X2 but don't have the tower cutouts. I made the mistake once, but the seller was nice enough to void the transaction before shipping.
Good luck on the cheap price! I gave up after about a year of searching and just had mine repaired.
Best bet is someone on the forum who bought an aftermarket cover. There are some out there because the OE covers stain the vinyl if it's got white vinyl.
'06 X2 MCX
"I understand why some people may not want to do this the way I have recommended but I can't understand the death grip some people have on a toilet plunger with a hose fitting." -JimN