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.
Cheers, but I wouldn't be able to run 32t with my rear derailleur. Maybe something like 12-24/25?
But needs to be a screw on freewheel... Which seem to be a bit rare.