I disagree with those who don't think the Dells can be a budget vacation. It depends entirely on when/where you go. If you go midweek, off peak season, it can be ridiculously inexpensive. I recently went with a group of three other moms and their kids (4 moms, 5 kids). We arrived on Monday and left on a Friday. We shared a 4Br4BA absolutely stunning presidential condo at the Glacier Canyon part of the Wilderness. Each family had their own spacious bedroom and bath, plus a large shared dining room, living room, and kitchen. 5 flat screen TVs, etc. It was a VERY nice place. It included waterpark passes for the 5 days. Grand total for all of us was $495, so split 4 ways $125 bucks. Tell me that's not budget!
We cooked most of the meals we ate in our condo...each mother cooked one night out of the four for everyone. I spent nothing beyond the $125 that I wouldn't have spent anyway (we brought food from home) besides a few bucks to play laser tag, and $6 to buy sodas once at one of the waterparks. Cheapest, funnest trip ever. We felt so pampered, and yet had spent peanuts. LOL!
Good deals can be found on ebay for the timeshares. Of course, you will pay substantially more for weekends and summer, but still, not terribly high if you can share the cost with other families.