.. that they can sell me.

Cheers.

don't think there very common but i believe extralite make one

E-13 also make some odd sized rings, not sure its as small as a 30T though

I know Salsa make one, but noone i can find actually has any in stock.

Shameless bump, just in case someone who works in a bike shop reads this. Saying that,I probably should wait till 11 o´clock, give them plenty of time to get out of bed, have a cup of tea, a few cakes and pump up a few tyres.

Think the Salsa one is only 5 bolt, as far as I know the Extralite Octaramp is the only 30t 'middle' ring available (it's actually designed to be run as the inner ring on a 2×9 and has no ramps or anything), to get it to work you have to file your spider down so the chain doesn't ride on the spider.