I would buy from someone that is has had their birds tested. Normally when you buy birds you quarantine them to prevent spreading diseases to your flock but since you don't have birds yet that really doesn't apply. Check out the middle tennessee thread on here it is allot more active than this one.
In my experience the temperment depends on the bird. Most of the hatchery birds I have gotten are not as docile as birds you get from an individual. The Orpington's are good birds and fairly easy to find if you are just starting out. Everyone on here has a favorite breed so its really is just...
I would definitly work on the lemon blue because they are a very pretty bird and not that easy to find. I had a pair a couple yrs ago but a hawk got them. The pen door was open and it landed and walked in the door to get them. Keep me in mind if you do get any now or later on. Good luck