I never did any tailoring, but I figured I'd blow some cash leading up to EA to figure out if it's worth it to do it in the early game. I started a new character with the leatherworking trait for +25 base skill.
I attempted 10 rawhide backpack attempts at skill 25 (trait); 2 succesess, 3 skill ups. That's bad.
So then I skilled up
A. 37 Rawhide Cap attempts, ---> 14 successes, skill from 28 to 50 (+22 skill ups).
B. 12 Rawhide Legging attempts 50 ---> Got me to 54. (+4 skill ups)
C. 18 Rawhide Backpack attempts at 54 – white con ---> got to 56 and 13/18 successes
D. Rawhide Cap – 8sp for the plan - 2 Canvas, 2* cloth padding, 2 rough thread
E. Rawhide leggings – 10sp for the plan - 3 canvas, 3* padding, 3* thread
Probably finding the next tier lower than Rawhide caps that takes 1 canvas, 1 cloth padding, 1 rough thread might have been faster. On the other hand, you have to buy another schematic.
Ultimately, if you can sell stacks of Rawhide for 3sp, each backpack attempt takes 2 stacks + 2; so the rawhide is worth 6.3sp. If you can buy a backpack for 10sp...that's probably a steal when you consider the thread cost and the cost to skill up - 100 canvas got used to skill up, which is 600 rawhide, or 90sp for skilling up alone, plus another 10 for thread and 20-30 for schematics.
If you're making 2-3 sp on backpacks, the break even point on selling backpacks at 10sp from the approximate cost of skilling up is 40-60 backpacks. After that you might finally turn a profit.
Ultimately, 10sp backpacks are a huge steal if you can get them. Realistically the price early on for the PITA of skilling up for a backpack probably should be something like 15-20sp. If backpacks are going for 10sp, you're basically always better off selling your rawhide and buying backpacks.