What's a good website to get HIDs for a 97' f150?
Specifically purple HIDs.

 

http://www.ddmtuning.com/catalog/HID_Kits-85-1.html

this is where soem of my friends just ordered theirs. nice b/c they offer a lifetime warranty

saw someone else post these guys up on another site. cheap prices, but not sure about anything else
http://vvme.com/catalog/list-s-10145-10146.html

 

I have the 6000k HID's in my F150 with Lightning headlights. You might want to stay away from the real blue/purple bulbs (8000k and higher). While they look cool you actually lose available visual light the higher up the color spectrum you go. My buddy had 8000k HID's on his truck and you could not really see that well. He switched out the bulbs to 5000k and he can light up everything so much better. I might switch my 6000k's to the 4300k's for some real night lights. I bought them on EBAY they are called Xentec's and they were $60 delivered.