I have had good success with the Kaces gig bags. I got mine for about $40. I don't think it's quite as good as the one George Kay sells. This bag has a little space length-wise to fit some extra things next to my keyboard. I keep my music stand under the keyboard because I don't care if the underside of the keyboard gets scratched. Next to the keyboard I keep a tupperware container that has my two sustain pedals, a/c adapter, my headset mic and cable. Next to that I keep my plastic floppy container that I velcro to the side of my keyboard when I perform. The Kaces bag has two zippered pockets for sheet music.
I've been pretty happy with this bag. I don't recall the exact size that goes with the PSR2000, but I'm sure you can find out with a bit of web searching.

It's good to know though that there are some great options for carrying around the PSR2000.
STay away from the Yamaha bag. It's flimsy and doesn't have enough space for accessories.
The bag George Kay sells sounds like the Rolls Royce of gig bags. I would go with that or the Kaces which I've been using for the last 2 1/2 years. Well, the first one wore out after 1 1/2 of heavy gigging.

Good luck,

Larry