Halogen Upgrades

[IndyNova]

So I plan on replacing my standard 7" headlight in my 70 nova to a halogen, for which i can then add HID's, but my question is this: what is th edifference in all the headlights(bulbs not counting), i've seen some on ebay for 20-30 a pair, but I've seen others for 70-80 for a pair. They all look the same, so i didn't know which route to take. I like the delta, but all the pics I've seen have the delta logo on them, and that looks crappy. I really like the Fesler Nova headlights, but there again, there more expensive than others. Any help is and alwasy will be appreciated. Thanks