I would get her, especially if you can talk them down to get a real bargain. I would ask for a video of her gaiting though and show it to a knowledeable person. People can mistake a stepping pace for a running walk and you need to make sure she does the running walk (or rack whatever she does). If the back foot hits the ground a split second before the front foot, then it's a stepping pace.
When you ride, all you do is ask to speed up (cluck) and they should go. That's how mine is trained anyways, no special cues. The gait should be smooth with a feeling of gliding on air. You should be able to feel her push with her back end and pull with her front end. If she has a good head nod (up and down) then she is doing a running walk, which is usually a slower gait. If she swings her head (side to side) it's a saddle rack, which tends to be faster than the running walk.
Let me know if you want more info. :)
Let your walkin' do your talkin'