Well, if you intend investing thousands of pounds in one, how much of a commercial market do you think you have in your area?
How high do you think you can push your domestic prices before the custy's tell you to go forth and multiply?
What kind of a marketting push have you got in mind to pick up all those lucrative commercial jobs?
Have you got all the health and safety paperwork in place along with method statements, risk assessments and all the other ballpoope needed these days? (oh and a waste carriers licence).
I wouldn't say mine is a particularly good earner as such because I have none of the above. It enables me to offer a service that otherwise wouldn't be done by me to more customers.