As the baby, if the age gap between you and the rest is big enough, you know what it's like for others to not want to play with you, to be teased and tormented, and to be left behind while everyone else got to gallivant around the town.
For me, this resulted in a thirst for friendship. I lived in the country so although I was allowed to have friends over, they rarely came because their parents would have to drive at least 20 minutes to drop them off and another 20 to pick them back up again. (It didn't help that I was always asking them the day of either, come on I was eight, what did I know about playdates?)
I'm telling you this because I have always valued friends at my parties more than presents. If you are doing it right, your children will feel the same. I prefer presents, instead of being the purpose of the party, to be a happy side effect. The last thing I would want would be someone to be embarrassed because they didn't bring a gift or felt their gift was too cheap. Token gifts are fantastic for most kids 6 and under, think crafts, stickers, bubbles, drawing paper, colored pencils, chalk, anything that is consumable that the kids will use up. Clothing, books and games are great for parents, although the kids won't always be thrilled. But I'm getting off topic, gifts are a topic for another time.
Give your children (and yourself) experiences, not things.
That doesn't mean you won't or shouldn't buy stuff. Trampolines, soccer balls, bikes and scooters, I would consider these all to be vehicles for experience.
Parks, sports (swimming pools are my favorite), and lessons, are all experience based gifts. I don't always have the time or money to participate in all of these. Sometimes you have to be creative. Do it yourself or pull someone in that can do it- if they are willing.
In terms of lessons, see if you have something to trade. Speak up. I happen to trade swim lessons for piano lessons every year.
Do you have the time but not the money? See if you can volunteer with your children. For example coach the soccer team, join a guild at the renaissance fair, be a chaperone or camp counselor. Be extras in a local film. ZappCon offers one badge in exchange for four hours of volunteering. The badge lets you bring two kids 10 and under for free. Use justserve.org for volunteer opportunities.
Be willing to support local businesses- they add variety and opportunities for something different to experience in your hometown. Every Thursday, you can experience new games by using the board game library at Crazy Squirrel Game Store. Looking to save money? Many companies donate tickets to silent auction fundraisers. That way you get a ticket for a cheaper price and your money goes to the non-profit you're supporting.
Let's hear it for season passes! The Fresno Chaffee Zoo starts at $55, Island Water Park starts at $49.99 and Wild Water Adventures $59.99. Now is the time to buy them-Wizarding World of Harry Potter comes to Universal Studios, Hollywood, April 7, 2016 season passes are on sale at Costco for about $95(for a limited time). If you don't get passes or only want to go once, ask you friends with passes. Tag along. Many passes offer discounts to bring friends along. Don't forget group rates- arrange before hand for better deals. Gateway Ice Center is $75 for a session and skate rental for a group of 10 if purchased in advance.
Travel- traveling can be expensive, but you have to put it in perspective and keep you expectations where you want them. If you do day trips, or travel to visit family or friends, the trip is really only going to cost what it takes to get there and back (gas or the plane/train ticket price). You always have to eat, even at home. You can bring food along if that helps. I always plan for at least dinner to be done at a restaurant when I travel. Plan ahead, the earlier you plan the better your deals will be. Travel mid week- Tuesdays and Thursday are best for flights. Borrow boogie boards for the beach. We are planning a trip to Yosemite using the A Child in Every Park program. Fourth graders and their families get in free to any national park in the USA. Go hiking, camping, and visit the river, if you live in Fresno you hardly have to drive.
Shutterfly and throwing it away even if it's an adorable scribble your kid will likely never care about.
Pictures, pictures, pictures. The majority of my childhood memories are preserved by photographs. It's hard to keep a memory without a strong visual in your mind. The best investment we ever made was buying a SLR soon after my first child was born. Ten years later it still works.
Pictures and videos are the best gifts to give your children and it is easier to do now that ever. Help them remember the good times and some of the super awkward phases.
Experience is what helps you level up, some shiny gear along the way doesn't hurt either as long as you are out adventuring.