I haven't used that one specifically. There are other brands that make those out there. They should all be around the 15-30 dollar range. I've installed many different ones in cars over the years. They all sounded about the same to me. When it comes to my personal cars, I don't use them. If I'm going to do a sub/amp in my own car, I will put an aftermarket head unit in. But it is all in how you setup the settings on the converter, amp and head unit in how good the car sounds.
But to answer your question. IF ordering from Crutchfield, those 2 links is all you'll need. OR if you buy the Basslink from Amazon, you'll also have to purchase an amp wiring kit (8g kit is fine for just the Basslink) and, of course, the converter. That answer everything for ya?