There are many USB to RS-232 converters but in order to use a new printer with the Clone, you need an RS-232 to USB converter. The website below sells such a beast. I currently have an old Oki serial printer hooked up to my Clone but it's old, noisy and slow and when it dies, it'll be hard to replace. With the Rs232 to USB cable, I can use a modern, cheap USB printer. This URL isn't the only place you can get a converter and I'm not endorsing them but I'm just presenting a possibility for you. You'll need a 9-pin to 25-pin adapter with the cable below as well. Enjoy!
http://microcontrollershop.com/product_info.php?products_id=5031
Tom L