Design wise, a $100 FPGA board with a bunch of peripherals won't actually be able to run many of them at once.
I have however designed a ~ $150 or so board (for prototyping) that has 10 bidirectional serial ports, a fast USB 2.0 port, and 20-30 general IO on 2mm headers, and runs on either a high or low precision 27MHz clock.
The rev 2 one also has an ethernet port, a TiWi module, and a RAM chip, and a better/cheaper clock, but those features add on a bunch of cost. Connecting the RAM makes for a much more expensive pcb.
I have however designed a ~ $150 or so board (for prototyping) that has 10 bidirectional serial ports, a fast USB 2.0 port, and 20-30 general IO on 2mm headers, and runs on either a high or low precision 27MHz clock.
The rev 2 one also has an ethernet port, a TiWi module, and a RAM chip, and a better/cheaper clock, but those features add on a bunch of cost. Connecting the RAM makes for a much more expensive pcb.