That cable is priced almost the same as a standalone slim USB DVD-RW drive.http://www.newegg.com/Product/Product.aspx?Item=N82E16827135256
An enclosure for the optical drive you removed costs about half that.http://www.newegg.com/Product/Product.aspx?Item=N82E16817707222
If you absolutely must keep the DVD drive in the laptop and 128 GB is just not enough space, another strategy (not so cost-effective) is to use the SD card slot as additional disk space. It's expensive (nearly the same $/GB as an SSD for a 32 GB SD card). On most laptops the SD card will not stick out when inserted. So you can just leave it in there. Put read-only files on it like MP3s and movies so you don't suffer as much from its slow write speeds. You need to weigh its cost versus ebaying the 128 GB SSD and buying a 256 GB SSD though.