I have glued between 5 and 10 pairs of tubulars myself, and I have never had the job professionally done. One shop near me that serves mainly racers charges $40 per tire; the other more general shop charges $20 per tire. I would bet that there's a difference in what glue they are using, how many coats of glue they apply, plus how much drying time they allow between coats, in addition to general expertise and marketing whatever prestige they have.
In terms of gluing yourself vs. paying, I'd say road tires put points in the doing-it-yourself column, and CX tires put points in the pay-for-it column. Road tires are pretty forgiving of sub-optimal gluing. CX tires are fussier and are more likely to roll if you screw it up.
Anyway, it is a messy job. You are trying to stretch a tight tire over a rim that's covered in tacky glue that will adhere to anything it touches. I felt a large sense of satisfaction when I'd finished the job, but then suffered some agony at times over a bit of tire rise or hop, any waving of tread lines, stray glue, etc.