For instance, a publicly traded company in your sector might be valued at a p/e ratio of 10 ( p= price, e = earnings). If your yearly earnings are $50.000 then your company would have a valuation of $500.000.
Also generally smaller companies go for lesser multiples than larger companies. It really depends on how much time and attention the owner has to put into it. In the case of a publicly traded company that is close to zero for shareholders (unless you own Yahoo). But for a small business you'll have to keep an eye on things even if you do hire a general manager.
The historical average is about 20. Growth companies (like Apple) were at 30-40+ recently.