Yeah, it’s possible to start up a web business with only $100 and make money. If you’ve =already= got skills worth about $70-120k/year, even in the present economy.
If not, expect to pay more and wait longer before things start covering their costs.
Never mind that it’s cheaper and takes less in the way of technical skills to start turning a profit in a whole lot of non-online businesses...
I say this as someone doing technical writing and digital publishing part time / at night after kids are down. I have multiple listings on Amazon. They take 33%, but I have no one to pay but myself.
OH-BOY-O-BAMA A DIORAMA OF OBAMA JOKES http://www.amazon.com/OH-BOY-O-BAMA-DIORAMA-OBAMA-Wilhite-ebook/dp/B002HRFBTY/ref=sr_1_1?ie=UTF8&m=AG56TWVU5XWC2&s=digital-text&qid=1280452917&sr=1-1
SETI in Reverse (Kindle Edition) http://www.amazon.com/SETI-in-Reverse-ebook/dp/B0011G4EDG/ref=sr_1_7?ie=UTF8&m=AG56TWVU5XWC2&s=digital-text&qid=1280453053&sr=1-7
Sirat: Through the Fires of Hell (Kindle Edition) http://www.amazon.com/Sirat-Through-Fires-Hell-ebook/dp/B0019D1966/ref=sr_1_2?ie=UTF8&m=AG56TWVU5XWC2&s=digital-text&qid=1280453053&sr=1-2