It is very hard to judge costs on something as fluid as a family tree. What information you are starting with will influence how long it takes to research the line back. What sort of surnames you have in your family may help or hinder the work – Smith and Jones are a lot more difficult than Footit and Tollfrey.
I charge by the hour for basic research at the rate of £14 per hour. I would estimate that in general it would take between 25-30 hours to form the basis of a family tree back to the 1830s.
If you wish me to research on a pay-as-you-go basis, I can report back at agreed increments. The cost of certificates and any travel expenses would be at cost.
I can discuss a package with you if you would like to pay in advance and receive a discount, for example receive a 15% discount for as complete a family tree as can be completed within 25 hours at £340 including six certificates.
I will always try to be as fair as possible and open and transparent about the work I have done.