I think you'll need to ask your dentist that question. My price includes attaching a permanent retainer to both sets of incisors, but I guess that just costs my dentist chair time. I'm not sure whether the price would have been different if had to get a lab to make a fitted retainer.
I think, unfortunately, it varies by dentist. Some people get the Invisalign retainers where you get three sets a year, other people get permanent wire retainers. It depends what your ortho prefers and recommends.
My initial price included the removable retainers, which I prefer since I like to floss easily. However, if I request a new one, which I'm sure I will because I don't think I'll like having the same one for an entire year, I'll have to pay like $50 for one.