The $25 one won't work unless you cut off the flange, which you could... but you should be able to find one without the round Apex'i flange for less and no extra work involved. The N/A version won't work either. Check out the Spectre one BT mentioned.
Don't order anything else until you know the diameter of the AFM adapter.
When you know what diameter you need search eBay for "aluminum pipe 90 degree" and look for the right sizes... that easy.
This really is a very easy setup to put together and install. It leaves a little to be desired with regard to filter servicing, but it's nothing terrible.
Here's an adapter:
http://cgi.ebay.com/ebaymotors/1987-...Q5fAccessories
Here's an inexpensive bypass valve that'll fit: Red:
http://cgi.ebay.com/3-Inch-76mm-Cold...item3368ad54c3
Blue:
http://cgi.ebay.com/3-Inches-Cold-Ai...item1e6447b794
(I prefer the AEM although this isn't a very easy part to f' up.)
Here's piping:
http://cgi.ebay.com/ebaymotors/3-OD-...item20b6148be1
(I like this seller's piping, nice and thick and the rolled bead is a bonus.) You may find that any piping you need isn't long enough on one side of the other, in that case you'll need to add one coupler and a short piece of additional pipe.