It depends on exactly what you have to do. If I do a leakdown test and am running 90+ in all 4 with no indication of leaks at the seat, I just pop the springs and replace the valve seals. Anyone can do that really. An 8" C-clamp from Home Depot, a Dremel and an spark plug socket is what I use for the compressor.
If I am going to swap springs and have confidence in them, height wise, same story. I only take a head down to the shop for two reasons. Valve guides, which yes I could do my self but don't, and regrinding the seats/valves. Regrinding the seat means cutting the valve stem, again, something I could do with some accuracy, but it's cheap enough for me to not bother with it. Where I live, I can get 16 valves cleaned on the lathe, new seats cut, valves cut, hot tanked, with new guides for 173.00, even if they are oversized. New oversized valves brings the price down actually because they don't have to clean them.
So it depends.
/brox