We MUST get a Christmas ornament every trip. If the one we like doesn't have the year on it already, we get it custom painted (worth the added expense for us as we'll keep it forever).
I get a mug every now and then, if it's really unique and fun. I do all the cooking in our home, so anything Disney for the kitchen makes me smile.
I like to get a wearable each trip. One year I got a tee (classic Mickey on a blue background), last year I got a pink 70s-styled zip up hoodie (because it was randomly freezing on our last day, but I still wear it often), and this year I'm going to be on the hunt for a vintage-style baseball cap.
We have a state shape magnet collection (get a magnet in the shape of every state we visit). I've decided we need a WDW one to go with, I feel like it's a state in and of itself. So that's on my list this year.
DS will be turning 4 on our trip, and I'm thinking we might get him started with pins. We bought some last year for him, but he didn't really care (he was only 2.5), but at least we have a couple to start with. If he's not into it yet, we'll just save them for next time.
If you have small children, I can say out of all the toys we've bought DS since his first trip in 2011, the small blue ray gun (with lights and sound) from the shop after the Buzz ride in MK (about $12) has been the BEST money spent. It's still going strong, it's not super annoying, and he still loves it and plays with it just about every day. There's also a 3 pack of cars from a shop outside of Test Track in Epcot. They're Toy Story themed and look like little race cars I guess. The Woody one is brown, etc. They are the kind that have a little assistance when they are pushed, the have some oomph in them. Anyways, I don't know how much they were (probably around $10-$15?) because my mom got them for him while we rode TT, but he still loves those and plays with them a lot after almost 2 years as well. Totally worth it.
We talk about getting the monorail train set every year because it's just so cool, but we just haven't pulled that trigger yet. I can order it online, and so far I haven't felt like I needed it once we were back home. It must just be one of those things that is so much more appealing when we're immersed in all that Disney magic.
I got a Dooney & Bourke wristlet (Mickey Balloons) in 2011 but I rarely use it unfortunately. Change and small things fall out from the flap (it doesn't zip). That was a pretty pricey flop. It's still super cute, but I haven't gotten the use out of it that I thought I would. The wristlets they have now zip, so I'm thinking of getting the sketch one on my trip this year.
the cheap little buttons they throw in a bucket at the cash register. I find the most unique pins in there.
