£1,200 is for the courses. Then there's the registration which I think is around £800 for 5 years (payable up front?). Then there's the cost of a flue gas analyzer (around £500) then there's the calibration costs (say £100 a year) then there's a requirement for public liability insurance to be OFTEC qualified (around £350).
Also the cost of oil pressure gauge, smoke pump, spanners, allen keys, nozzles, flexible oil lines, etc. To get yourself going you're looking at a cost of around £3,000 for five years (when you have to retrain, and re-register.)
You'll be looking at say £50-£120 for an oil service, depending on your local market and it takes many of these to cover the initial costs and start to make a profit, but installing a new boiler makes you more money so it's not too great a hit after a year or so.
When I told my local inspector that I make a loss in my first qualified year by being an OFTEC chappie he was surprised and offended. The reason I am qualified is I didn't want customers phoning me up and saying "My heating doesn't work" and with me having to send them to another competitor.
Now, with hindsight and experience, it's one of the best things I ever did in my plumbing career.