We have a small slide/climber thing. I believe it is a Step 2 and we bought it for $35 at a garage sale. It is a square, with 4 little "ladder like" steps that go up to a platform with sides. The ladder is on one side & the slide is on the other. You can climb up either side & squeeze under the sides. There is also a doorway and a little "hideout" underneath. We got it for my daughter's 2nd birthday.
My kids have always loved the little lawn mower & wheel barrow. We got our lawn mower & wheel barrow at Deseret Industries for $1 each. We also have a homemade sandbox. I got a large underbed storage container (with a lid) and 2 bags of sand from Home Depot. It is on the small size as far as sandboxes go, but I can drag it to the front yard if I'm working in the flower beds and the kids can play right by me. I'm into the whole thing for less than $10! We also got it for my daughter's 2nd birthday. She'll be 6 next month & still loves to play with it (now she's too big to fit inside, she & her brother (2) sit next to it). I have a friend that bought 2 hard sided swimming pools. One a bit bigger than the other. In the smaller one, she put the sand. Then, she used the larger one as a cover & a pool. When they wanted to use the pool, she'd take the "cover" off & fill it up. When they were done, she'd dump the water out & cover the sandbox with it. She put a couple of pieces of 2x4 across it to keep the wind from blowing it off.
We play A LOT with sidewalk chalk, bubbles, and balls. Hoola Hoops are fun too. We have done "obstacle courses" with them. My kids like to jump through them, try to throw a ball into the circle, and jump in and out of them.
If you have a large tree, you can go get one of those baby/toddler swings and hang it from the tree.
My kids have also loved riding their trikes/bikes. They're hand-me-downs or bought from KSL classifieds ($15 or less). Good luck & have fun! This is the best age for exploring and having fun outside! (It only gets better as they get older too!)
Enjoy the spring & summer with your little guy!
Shellie