While it's in Chicago, just on the outskirts of the city is Ocean Design. They usually have a pretty good selection and he's willing to get fish in that you want.
I believe there is one other place that's routinely recommended in Lombard called Tropicquatics. I haven't yet been there myself, but I see folks always recommending that shop.
Another I haven't been to in ages is Coral Reef Pet Center in Norridge on Lawrence Ave. If you go there, Ocean Design is like 10 minutes away so it might be worth a quick stop.
Fish Planet as mentioned above is another that's frequently recommended. I haven't yet been there either.
ETA: I don't know if your reason for avoiding Chicago is similar to mine, but Ocean Design is maybe a couple miles east of Cumberland Ave. It's probably one of the only two places I still go to in the city...the other is to get my CO2 refilled, otherwise I avoid the city like the plague.