There are way, way more variations than 3. There are numerous types and designs and brands, although many of them may or may not originate from same factory, but as stated, if you are at all interested in trying one, it would most likely be wiser to try one with a dedicated battery pack. The kits or light heads and batteries range from dollar store quality to mid range and then top level $100+++. Some people swear by buying the cheap light heads(or multiples) then buy decent battery packs and chargers. I could give you some links if intetested. I've never bought from ebay, but had good luck with amazon, but I cannot speak to battery runtimes as I never ride more than an hour rarely.