Some time ago @Boxdog pointed me to a uCPBX in Bulgaria. They are reselling various small Asterisk systems based upon the Astfin project. They have a few variations on the IP04, including an 8 port variant (IP08 = 8 FXOs) as well as 1 or 4 port BRI capable versions.
The design of the base system supports adding interface ports through the use of little daughter cards. I believe that their daughter cards are compatible with Digium’s TDM-400P card. The cards even use the standard DAHDI driver making installation especially easy.