Improvisation can be part of the fun. It certainly is a challenge. I did a lot of it when I was getting started (haven't really quit -- I'm a garage shop inventor at heart) but I suspect you're going to be in for a lot more than I was . You should be able to get bloom numbers from the manufacturers. Find a website contact number or email. Bloom numbers are as important to cooks as they are to photographers.
I'll inflict you with an opinion, though. Given the cost of silver nitrate, the cost of all other ingredients falls relatively to free. I'd invest in the extra shipping costs to get good materials as you get started. It will more than pay off.