Picked a couple of Holdalls up from Aldi yesterday, perfect fit for boot of the e89 with a little space for a couple of coats or something small, they have wheels and a pull out handle and at £15 each as cheep as chips.
SWMBO & I have just been away for a week with the well-known £199 German/made-in-China Z4 cases. These have at least one advantage, though. The wheels are at the wide end, not the narrow one, so they don't flop over when you pull 'em.
Just bought 2 from my local Aldi (Winklebury Basingstoke). There were two more in the dumpster. I think the website saying 'no longer available' may be because they have just (last week?) stopped selling special buys online - you have to go into the store.
I have a large, rigid plastic Samsonite suitcase that JUST fits in the boot and allows the roof to be lowered, but it is very heavy when full; these are a much better option. Cheers.