Cheap flights to Oshkosh?
 

I know it isn't strictly about private flying, but I'm planning to do Oshkosh this year and can't seem to find any cheap flights yet.

I haven't been for quite a few years, but last time managed to get good deals to Chicago and car hire sorted out reasonably well in advance.

Cheapest flights that I can find now are about £500 for Air-Venture week, although sub-£300 flights are available for earlier dates upto June.

Any inside knowledge on where/when/how to get a good deal for Air-venture week?

Book early!