I note you are from my neck of the woods.
Mrs sandb and I travel there several times a year.
It is more often than not as cheap to fly out of Madison or Milwaukee as it is from Chicago.
Although you can use American,Delta,NW and CO from these two places, we usaully fly NW and CO codeshares:
NW/MSN to MSPorDTWorMemphis
NW to IAH(Houston)
CO/IAH to BZE
Typicqally 6:30 AM to 2:30PM plus the puddle jumper.
The fares are fairly constant ( within $50 from these locations) and you will note that the $429 fare now is reasonable, typical, and the same wether you fly out of ORD, MKE or MSN