But if you pick up a used (or even new) set from ebay or elsewhere would it be really poor form to take it into the LBS and ask them to set the bike up?
nope, they have standard fees for this.

Do they normally charge heaps to do it?
to put together an entire bike, a shop i like charges 300 bucks
a shop in texas charges 100.


Is it possible to read up enough and do it yourself?
yes, but not me, i'm chicken and not mechanically inclined.