Whoa - you got a dedicated thrower TK61 and a flooder TK75 that has some throw listed together as your choices. You seem to be leaning toward Fenix in all your choices. There are cheaper alternatives around for side switch lights, though the TK61 is king of throwers in this price range, and the TK75 is a great light. For the TK41, the specs look quite good for an AA based light.
Why do you care about local availability and cost for 18650's? I'm in NY, US and I can't find 18650's anywhere locally and I have a ton of 18650's - all ordered online from China and local US online retailers 3,000 miles away.
There's a bunch on info in this thread: https://budgetlightforum.com/t/-/23282 on throwers.
I'd recommend this:
Yezl Y3 from here at WallBuys - side switch, can use one 26650 or one 18650 cell, throws well at 62.6 kcd stock, which is a 500 meter range, details of the light as purchased here (stock form) in post #77: https://budgetlightforum.com/t/-/24076