Don't worry too much about the cambelt being done at a specialist. Worse case scenario is you buy it and have the timing checked by one of the specialists and corrected if needed. Also, the dephaser only needs doing if it's making a noise. It may well be fine and won't need changing for years to come.
It really isn't as big a job as people make out, and i'm sure there are plenty of competent garages that do the job well. It just happens that we only hear about the ones that have messed up.
If the rest of the car is perfect, or is exactly what you are after then I'd say go for it. Don't be put off by that one thing.