Yes you can still buy Seeley's Porcelain!

Seeley's Porcelain Slip




This is the first porcelain I started out with over 40 years ago! If you have not used Seeley's before, I included an excerpt from their website. The emphasis on the extended firing range is mine. If you have a kiln that runs a little on the hot side or even a little on the cold side, the fact that this porcelain is more forgiving of temperature differences can make a huge difference and the percentage of unusable pieces.

 "For over 50 years, dollmakers and porcelain artists have used Seeley’s formulas of porcelain slip to create the world’s most beautiful pieces.  Artists knew that when they started with Seeley’s porcelain slip, they started with the best.  That’s because only the finest ingredients were used, and each batch was tested to make sure it matched exacting standards.
The finest porcelain formulas, once produced by Seeley's and New York Doll Products, are now manufactured exclusively by New York Dynamic Porcelain in upstate New York. Using formulas established after extensive testing by ceramic engineers and experienced artists, we blend our slip thoroughly and then subject it to a two-step filtration process.

• Easy to mix and pour!
• Strong in greenware and resistant to cracking.
• Extended firing range makes for no-fault firing.
• Our slips fire to (Cone 6) bisque that's beautifully translucent." 

http://www.nydpshopping.com/porcelain-slip-3-liter-bags-only-for-small-orders-shipping-within-the-u-s-a/ 

Each bag costs from between $17.00 and $20.00 depending on the color. My favorite doll color French Bisque is only $17 per bag! And you can ship two bags Priority mail for $16 or three bags can be shipped together for $24 via Priority mail.

They are also happy to ship overseas with one rate for Canada, and another rate for the rest of the world. I would suggest if you are overseas to check with your local potters to see if there is a source of porcelain closer to home. Just remember you want a cone six porcelain slip as many of the potters will be more used to dealing with a higher cone ten porcelain.