HK used to make them prior to 1989 when the first president Bush banned their import. The HK made ones would be pretty expensive still even though the manufacturing ban is gone (the import ban is still in effect). See the website below for the current state of things
There are probably going to be more MP5 type guns made by other makers now that the AWB is dead. I would not hold my breath waiting for HK itself to offer these again though.