Take some time to fill out the form, its in the stickied posts in this section, people will have a better idea of what your after, and take some time to tell us of what you need from this light, theres loads to choose from but we cant recomend without knowing more tbh, 100usd is a good budget to get a decent light so Id suggest getting a known branded light so you get good quality, you will still get something bright for that price.
And may I ask why only ebay? Nothing wrong with it but your limiting yourself a bit, loads of other great sites to buy from, if you tell us your country of residence (I am assuming US though as the currency listed is USD) we can recommend a few places to look at, ebay may not be the best place price wise ect.
As your hiking I would guess something floody, but still with some throw, it seems you already know about 18650's I would go with that over AA much better for proformance, however I suggest getting good quality charger and cells, if you do not already have that set aside some of your budget for that as well, no point haveing a good light and useing *****Fire cells in it.
Maby do some reading on lion safty, but dont get scared off by it, a lot of it is overhyped, thats not to say its safe though, but like anything it is safe if you follow some simple rules, 99% of people if they follow basic commen sense and intrsuctions / ruel with good quality cells and charger wont have a issue, its normaly usser error or bad quality charger and cells or a combination of all of the above that leads to the horror storys! Even multicell lights are fine, despite what some members will have you believe, your Laptop if you have one likly has muluitpal Lion cells in it, and how often do you hear of them exploding!! not very often unless something stupid is done.
other than that, enjoy it here, have fun, enjoyr whatever you decide to get, and be aware its unlikely it will be your last XD!
Im not as bad as a lot of people on here, but I have over 25 torches in my house, although only 10-15 are decent ones.
oh and WELCOME TO CPF!
Edit look into spark headlamps, there meant to be good, I don't own one though.
