You can buy the parts anywhere you want to, a local dealership, a friend's dealership, or an internet dealership.
I ordered mine from Bill Jenkins at Signature Lincoln Mercury. I got the Ford and VW parts needed for less than $400 US shipped. You can e-mail Bill at parts@signaturelm.com, but your best bet is to call the main number (800) 876-3280 and ask for Bill Jenkins.
I have no affiliation with Bill whatsoever, he just happens to be a really nice guy offering the lights at a really good price.