Here is my logic...you pay a dime/foot, use 10 ft, i dont use clasps, it takes maybe 10-15 mins of tying! I have spent 1 dollar and 15 mins of my time and i am going to mark that up 800%? Ridiculous! I cant keep up with demand and i am making money! Just saying!
IMHO you're setting your cost (not selling price) too low. You're not considering all the factors.
You have a dollar in materials. What's your time worth? $10/hr? What did you pay for that show space? $50 If you're selling online, what's that online presence costing? How many bracelets will you sell at that show? 25?
Plugging those numbers;
Materials $1
Time $10/hr for 15 minutes = $2.50
Space $50/25 Bracelets sold = $2
---------------
Total $5.50
And that doesn't include transportation to and from the show, supplies, displays, tables, sinage, maybe an easy-up for some shade, etc.
Off the top of my head at $8/bracelet you're making less that 50% not 800%