So idk what you’d define as not bank breaking but ill assume you wanna do something thats fun and free:

Obv the parks which from your responses it sounds like you’ve done that plenty of times

Museums (look up different ones, you might find one you like!)

You could go to the ice rink and maybe catch a local game of hockey maybe. Unless its MSU its usually free to just walk in and watch.

Top of the parking garage in downtown area (across from hurts donuts): maybe dangerous, but when there arent people parked up there doing drugs or whatever else they may be doing; its a beautiful view of springfield and downtown area. A great place to relax for a few minutes if you’re just tired and need a break from driving. Also a great place for pictures to show off your home town ;)

Idk if you’re a people person or a “i want to be alone” person but if you’re the first, maybe you could take a stroll through the mall. You dont have to buy anything but just go through and look at items (might help you find some christmas gifts!)

If you dont mind a little drive. About 25 minutes south of springfield on 65 is busick hiking trails. Its not a fancy organized trail like dogwood canyon further south. Its more of a untouched nature with a few designated trails. Great way to escape reality and just enjoy yourself and your own company. Dont get lost though, and be aware that there could be bears.

Some ideas that may cost some money:

Horseback riding (royal creek farm, unknown price)

Rage room springfield (i think $50 is the cheapest price they offer)

Batting cages (fun acre gives you 5 swings a quarter. I like to go there to escape sometimes.)

Zoo

If you have friends you wanna spend time with you could try the escape room or mini golf at fun acre or the new place on sunshine (fun acre is significantly cheaper).

Look at the christmas lights around bass pro

Go to an MSU sporting event (if they have any)

Horse carraige ride (Shires for Hire)

Those are just a few things off the top of my head