Got an Answer?
Yes, I agree; pick up on what they like doing and get things that compliment that.
I used to hit the jackpot by noticing particular toys /sporting gear my son tended to play with at other people's houses that he didn't already have, made a note & asked him simple strategic questions while he was playing, like characters he liked the most in the set his friends had, or which colours he liked the best.
I didn't have a lot to spend on him when he was a young child, so sometimes the presents were cheaper versions (unless they were Star Wars toys/ Lego - I kept an eye on prices & when they were on sale, I'd layby them) but he seemed to enjoy them nevertheless.
Now he's a more discerning young man of 15, he gets a small gift that I have determined that he really wants (I'm lucky, he actually talks to me most of the time) & a Prepaid Visa gift card.
We make a day of it, have a shopping spree & a Hungry Jack's feast with one or two of his friends beforehand. (Teens are much more amiable after being fed & watered) ;-)
Stab in the dark... but kids seem to really love those bloody hatchimal toys? Boys and girls get a kick out of them.