Not sure how far you want to drive, I know there a quite a few in Chicago.  Have you ever looked into mail order places like rodentpro.com or themousefactory.com?  They will deliver frozen to your door.  I believe rodentpro is in Indiana.  Check them out.  If you have Herp friends close by you can go in together.  Let me know what you think.  Good Luck.

While I'm not in IL, I know where to find lists of herp vets:

http://www.herpvetconnection.com/illinois.shtml

As for feeders, I believe you said you have a local expo that's once a month (I could be wrong), if so most expos have someone there selling feeders.  I would just stock up when going to the next expo, until then you have a couple different opinions.  You can buy frozen feeders from Petco or Petsmart (most pet stores sell f/t), but they usually are very over priced.  Since you only have 4 snakes this next option may not be the best since you'll have to pay overnight shipping, but there are several companies you can buy f/t from and have them ship them right to your door.  I personally like RodentPro best, but that's just me.  What you can do is see how many you want to buy and then divide the shipping cost to see if it's more cost effective to buy from somewhere like RodentPro or a local pet store.

Send a PM to CGMa or Jaybee on here. It sounds like they are not too far from you. They might have some leads on a good vet.

There are lots of herp shows in that area.  Im sure  you can go find a bunch  of rodent vendors . Or look on the fauna classifieds  under feeders  if you search I'm sure you will find someone local ..

The thing with the guy I bought mice from, the first time I went to the expo and bought from him, this being the same guy who sold me my amel Koi I was happy with his mice. Not so much with his snakes. When I went back he wasn't there though

I am in crystal lake, and i get mine from the expo in wheaton. I know that one guy is not selling there anymore, but there is another vendor that sells them as well. as for vets i have never had to go but in dundee they have a snake vet which is close for me