They often pop up on ebay for around £90 including some ram installed, usually anything from 32MB to 128MB.

Amigakit did have them for sale until recently, but they don't have any on their site at the moment. www.vesalia.de have also often had them in stock. Sadly they don't have any either.

Another make you could get is the Viper 1230 Mk V. Very similar product and there is one currently for sale on ebay here.

Another make of 68030 accelerator was Apollo, which is also ok to get. Although both of these makes are not as popular as Blizzard as most people claimed their build quality wasn't quite as good.