the idea comes from my personal issues when using some products. i think $100 is enough to build the startup.
If it's so low, compared to a regular job salary. Why do you need it?
Just work on it on your free time.
If you don't need a large sum take a loan.
The traditional way is the "Three Fs". Family, Friends, and Fools.
If you don't have access to capital (via a loan, mortgage, personal savings, etc) then you ask your family if they can give / loan you the money. Then you tell your friends that you're starting a business and would love their support. Finally, you go online and make a Kickstarter to try and part idiots from their cash.