Best? Hotshot
Affordable? That is a different story.
A Gen 4 Hotshot header can be found BRAND NEW for about $350, give or take on the location of your choice. Sometimes a bit cheaper, and sometimes more expensive. A lot of the Hotshots come with copper gaskets, which are very nice to use. Finding a used Gen 3 Hotshot header will work just fine too.
So... cheaper headers will work (My Focuz header does the trick), but you will see a couple more ponies and tq from a Hotshot. One noticable difference between most other brands and Hotshot is the quality (HS having ceramic-coating).
Hope this helps. Also, see a couple previous threads about headers for the 1.6L...