I just barter a new cockerel every year, and have pretty even hatches. I only ever use the incubator nowadays, haven't had a proper broody for the last two years. I think that if you have an incubator (mine is 24 eggs all singing-dancing etc, so doesn't really take much looking after), you can do all sorts of chicks, ducklings etc -we have two geese wandering round as a result of getting surplus eggs), and after a couple of years you should break even on the cost.
However I don't do eggs through the post - all homebred or from someone with a similar set-up to mine and collected in person.
One big advantage of breeding from home-reared stock is that the danger of bringing in disease and susceptibility to disease (or animals carrying disease as a result of live vaccines from factory produced stock) is much reduced. After having a bad year last summer (cockerel wasn''t up to scratch and weather was really quite rubbish) I decided to buy in 5 replacement POL... at 18 quid a bird... they went in with my homebred hens of similar age (after isolation etc), and of the ten hens in total I have got three left 8 months later... all the homebred birds died from something and even two of the bought-in ones keeled over!
I also run two flocks with a cockerel each, and non-productive hens is dispatched every autumn (even though scrawny the breasts and legs still make a good coq (or hen) - au-vin or a curry.
Seems to work - but mine are mongrels and I have no interest in breeding pure.