Hi Mike,
Will your bimacs accept good quality frozen Gulf shrimp?
My current method is to phone the fish market (I use TJ's, at the corner of Preston and Forest in Dallas, since you're in my area) and tell them to start thawing out a pound of gulf shrimp - in about 1/2 hour, the shrimp are unfrozen enough to be pulled off the 5-lb chunk, but still partially frozen. I buy a pound at a time, rush it home on ice and in a cold proof container, and stick all the shrimp in plastic bags in the freezer. Then I can thaw out a couple a day for Ollie. She likes them very freshly unthawed.
I think whatever you choose, it's going to be expensive to feed two bimacs well (and you must keep them well fed if you have two in a tank, otherwise they start looking at each other). Look at it this way - it's probably not more expensive than feeding a large dog or two.
If you vary their diet, you can stick some cheaper types of food in - like frozen fish. I hope you eventually succeed with the feeding stick. It's a great communication tool, too.
Nancy