Agree. Virgin australia mel-lax fare $1180 available this morning ( Sunday 30th)- sh@@t I paid $1200. Add a southwest rt lax-mke for $500. 8 nights at au$80 a night. Car hire $350- and having a car is actually useful. Join eaa and airshows entrance is $140 for the week. Wreck your kidneys at Kelly's bar in the evening. So a DIY approach would cost you around $2700 but in fairness the tours do more than oshkosh.
Go arguscarhiredotcomdotau for the car as they include all insurance- booking on a us site will not do this.