We love to do miniature golf when we are down there. There are quite a few of them around to choose from, even a few on Disney property. You can usually find coupons for a dollar off each round (for the non-Disney courses), so that could help with the budget.
A couple of years ago we did a trip to Bok Tower Gardens. It's not super exhilarating, but it was a nice break from the chaos.
If you feel like venturing into the Downtown Orlando area, there is a little lake where they have swan boats that you can paddle around the lake in. There is a walking path around the lake. Sometimes they have events going on around the lake, so you might get lucky and be able to participate in something unexpected.
We also like to do a trip to the Cocoa beach area.
Have a great trip!