I've been ordering FP4+ from the Ilford annual special order. They'll cut HP5+ too. Adox and Foma should be able to do a special cut for you as well without requiring a very large minimum order, and for color or for Fuji/Kodak emulsions, Fuji and Kodak will do a special cut, if you can make the minimum order, which is substantial (on the order of $10-15,000 USD). Some people have been using the internet to organize custom orders of various emulsions, as long as they are already available in sheet form in some format, like Tri-X, T-Max or Provia 100F, etc.

Ilford makes a high quality product, and for participants in the annual special order, they don't require high minimum orders, so it's an attractive option.