First off, if I were you guys, I'd look up and do some research at ATF, maybe even make some phone calls, no, DEFINITELY make some phone calls, and make sure you aren't accidentally building a bomb or IED. Follow me here?
I'm sure there's some things you can make that are better than store bought and cheaper, but make sure it's legal.
I'd recommend getting a good book on making fireworks. Believe it or not, the "Poor Man's James Bond volume 1", which is a book on how to make explosives, convert semi's to full auto, booby traps, etc., ALSO has about half of the 400 pages dedicated to fireworks. It's a reprint of a book about 100 years old, but nothing's really changed. They still build 'em the same way using the same ingredients for the most part. Tells what to use to get the right colors and designs, etc. A really good read for anyone wanting to make fireworks. And be careful, mixing of some of these ingredients can cause spontaneous explosion, particularly red phosphorus but there are others.
I'm guessing you guys like your fingers, so be careful and follow instructions to the letter. And call ATF to find out what the rules and limits are, and look around on their site too. CYA, always cover your ass.
Be careful and good luck!
Oh, FWIW, I have a copy of that I got off Scribd. You can sign up for a free month of Scribd and do it yourself, then it's $9 per month. Or if you PM'd me and mailed me a USB thumb drive with a stamped, self addressed return letter, I'd be glad to copy off all my manuals including all four volumes of the one above. I have some military manuals I downloaded, and I'll include all I have and you can keep or throw away whatever you like. Some interesting info, but mind you a good deal is illegal to actually do, so be careful, don't convert weapons to full auto, don't build IED's and call ATF for guidance.