well you can make any of the lights PCs, T5s, Halides
basically your just buying the ballast, reflector(s) bulbs, endcaps yourself and mounting them in your hood, they generally arnt "pretty" unless mounted in a hood/canopy
you can also get packages that come with the parts. im not saying retrofitting is the way to go and im not saying its not, im just letting you be aware of your options. i would hate to see you dish out a few hundred on a light then decide you want something better or if you buy something and a month (or few) from now want to upgrade, you dont have to get the biggest baddest thing but get something that works for you (and your budget) that you will be happy with instead of buying one now and 4 months from now buying something better. i hope that makes sense. just take your time and find that perfect fixture that fits your needs.