I'd say go to walmart and find yourself a tub (a sturdy one, not the cheap flexible ones) around 10-15 gallons and a HOB style filter (hang on back). You might have to do some trimming to the lip of the tub to get it to hang right, but it will work. And that's it. Plug it in and go. The whole set-up should cost you less than $30 which is what, 8 dozen shiners or so at the bait shop? Lots of savings can be had by catching your own or buying bait in bulk then holding it yourself. If you want you can buy a simple glass 10 gallon aquarium at walmart for $10-$15 instead of a tub. But just make sure you are careful with it, cold and glass don't go well together.
If you are going to hold them any longer than 3-4 days, air bubbler only is out of the question. Get yourself a power filter, the bubbler ones are no good for what you want.
Just for reference. a 15 gallon tub, and a 20 gallon HOB filter will be plenty for about 5 dozen shiners held over long time. It will overnight up to 10 dozen smalls.
