Hi flamanar, welcome to BLF. I'm still a noob too, and this is my take on the battery question, based on hours of searching and studying what far more knowledgable members have written.
Basically, batteries are one area where I honestly wouldn't bother trying to save a couple of dollars. Yes, there seem to be periodic bargains out there, but with cheaper batteries (like with cheaper flashlights) the whole thing becomes more of a lottery. QC goes down, along with reliability and, usually, performance. I've seen many 'deal alert' battery threads here at BLF which suddenly get updated to become 'warning' threads when someone gets a bad batch of the - up till that point - recommended batteries that started the thread.
I guess for flashaholic experts who know what they're doing and need to buy, say, two dozen batteries at a time, then a saving of 2 or 3 dollars per battery is a worthwhile venture, but until I reach that point (probably never) I'll continue to spend a little more and play as safe as possible.
Li-ion chemistry, which applies to 18650/14500/10440 etc batteries, seems in any case to be something of a questionable issue. Here at BLF there are members who won't use these batteries on safety grounds, and there are others who regard the potential risk as being so low as to be not worth worrying about. Personally, I use li-ion batteries but with caution.
And it's not just about safety. Budget batteries usually don't last as long and often won't perform as well as better quality ones. It reminds me of running a high performance sports car on cheap motor oil. Why? Just my 2 cents, of course.
FWIW, I use this charger, reviewed here (and by others at BLF): https://budgetlightforum.com/t/-/4442 which I bought from here: http://www.hkequipment.net/index.php?sp=&p=6&cat2=150&cat1=59&cat0=2&id=1045&cat1=59&cat0=2&new=&more=&s=c98de9a8dc28171caf15ce26d10c5c9a&lang=en
It has inbuilt protection against overcharging batteries, which alone was worth a few extra bucks to me. And I use these batteries: http://www.qualitychinagoods.com/2pcs-xtar-18700-2400mah-rechargeable-protected-batteries-p-1929.html
But, as I said, I'm still new to all this and I based my choices on reviews and help from here at BLF. Boaz above gives good advice re using the search facility; there's a wealth of info within in these archives.