Honestly, the 250 dollar one is the exact same chinese kit that sells for 80 on ebay in other auctions. The ballast is the same, the bulbs are the same, and the wiring is the same. Look at pictures and you will see they sell for even more than that from other vendors.
I just installed one of these
http://cgi.ebay.com/ebaymotors/HID-XENON-CONVERSION-KIT-H1-H4-H7-H11-9005-9006-9007_W0QQcmdZViewItemQQcategoryZ36476QQihZ016QQite mZ260182172927QQrdZ1QQsspagenameZWDVW on my wife's lexus with great results. (notice it is the same kit as the 250 dollar one) and installed one in my old tundra 3 year ago, my brother has it now and they still work.
I will be buying another one soon for the new truck, and will buy the same kit from whoever is selling it the cheapest on the day of purchase. Since they are the same, they usually to manage to drop the prices 10 dollars ever few months as someone else battles for the low ball vending.
In my porsche, I opted for the 1500 litronics, the light output is the exact same as the 70 dollar lexus bulb. I will post a side by side pic soon.