Yep. If you can throw a cast net pretty well then you can catch all the minnows you need yourself for free, but of course, they won't live as long as the store bought minnows. You can help them out by changing out the water very frequently, adding a handful of non-iodized salt and using a larger bucket, but they still won't live as long as those tuffie/tuffy minnows you get at the store.
I know you're fishing down at Pickwick and I'm not as familiar with that area as upper Pickwick, but if the bait shops over there are like the ones up river then they sell out early many days so it's always handy to throw a cast net in the boat just in case you get stuck without an option to buy. Honestly, a couple of weeks ago on upper Pickwick the schools were so huge that you just had to be able to get the net to open up enough for it to land halfway right on the water and you would get some minnows. It only takes a little bit of practice with one to get good enough to do what you need to do so don't be afraid to get one and start throwing it. Hell, I'm a girl (and not a very big one) and I can handle most cast nets well enough to get the job done so I'm sure you'll be a pro in no time. lol