Yup, the only ones I've found are either NOS or the 11-32 ones at SJS. A quick gander at eBay finds this and this.
To be honest, you're probably better off moving over to a freehub. By the time you have 8 sprockets hanging out over the axle it's quite easy to bend them.
I have an 11-32 if you really want to relax? £10, PM me if you're interested.