I too am home based as a Professional Engineer in Private Practice. I've been doing it for 15 years now and it's enough to support our family of 5 and the odd Disney trip

Like drag n' fly, I'll answer in the same manner. Not that it can be done by anyone who is not a P.Eng., but to give further details on what is done.
What was the start up fee? For me the cost was fairly low approx 1500.00. Back in 1995, that was very econimical. We already had a P.C. just getting started with dialup internet. Used to receive mailings from prospective customers to provide quotations and courier my quotes back out, but it's mostly done by email now.
What are your committments/quotas? Usually Up early, around 6:00AM to work on projects, but stop at 7:30AM every morning until 10:00 to take the kids to school, handle Kiss N Ride at the school, and have breakfast with DW and DS (3). Then, after our morning meeting, it's back to the basement office (sometimes referred to as the 'dungeon'). After supper and the kids put to bed, I'm usually back in the office on average 2-3 hours.
Most times I work late evenings and weekends to provide my clients what they require. For my business travel, I try to get as much travel done for as many clients as possible to reduce extra hotel costs. Because of that, I have significantly fewer Holiday Inn Priority Club points this year.

What kind of money do you make doing it? I charge $100.00/hr plus the McWimpy HST. That is what I charge, and work into my quotations, but, depending on the project it may work out to between $60 and $150/hr.
Is it easy, hard, time consuming? No! Yes and Yes! I agree 100% with that. Some really busy periods and some very demanding clients occasionally make you feel you don't see your wife/kids and your office is just below them! Having to wait for invoices to be paid to you is sometimes stressful.
Any other pros/cons to it? Freedom of my time is definitely there. Regardless, when we go on vacation, I always bring my laptop. When the kids sleep, I check emails and plan my week with my clients for when I get back. DW tolerates it as I only work when the day is essentially done.