hi there,
scrypt need a more memory , in opposite of sha2 mining ,
and Choosing FPGA as mining scrypt this very costly.
getting 1gh/s for scrypt this equivalent ( over than 650 GPU card working together)
if you want to design your own asic this going to be very costly remember each scrypt unit hashing need 32kb of memory.
if you're intersted we can talk more
best regards