If you have an oddly-sized instrument, and you take it out of your house more than rarely, you should get a custom bag from Mooradian.
Way back in January or so my faithful microKorg died and I replaced it with a Waldorf Blofeld. I picked up a generic 49-key keyboard bag to go with it. This bag was crap. First, the bag was way too big for the Blofeld, making it floppy and awkward to carry. Second, the flimsy hardware on the strap broke within a couple weeks.
Long story short, a couple months ago I stumbled across Mooradian, who will make a variety of bags to order. I ordered a bag for the Blofeld. It came to under $200 delivered and arrived in about 4 weeks.
The hardware and craftsmanship are top quality. Most importantly, the difference from the ill-fitting bag to the properly-fitting bag is shocking. My instrument feels ten pounds lighter, probably just because it doesn’t shift around when I carry it.
I recommend them highly.