An H4 headlight conversion consists of the H4 lens enclosure and waterseal boot. Most kits come with bulbs (H4 bulbs) but you may want to upgrade the bulbs because many kits come with those crappy Arctic White /Hyper White bulbs.... IF... you want to go with the H4 conversion, spend the extra money and get Sylvania Silverstars or PIAA Super Plasma bulbs. You will probably end up spending about $120 or more for the conversion plus bulb upgrade. It is completely plug and play.
If you decide to go the cheaper route, I suggest getting the Sylvania Silverstars Sealed Beam. This will cost about $50 .Probably a little bit less. Our sealed beam size is H6054. I HIGHLY recommend the Silverstars sealed beam. They are quite bright and I don't see much more benefit in getting the H4 conversion.
And in case anyone says "well you need to just get the conversion, it owns".... I DID have the conversion. I used it for a while. Then got the Silverstars sealed beam to compare... I love them.... I sold my H4 kit soon after. Only lost a couple bucks so no big deal.
http://www.autobarn.com has the sealed beam there... I couldn't buy them locally because none of the stores that I have been to carry them.