No direct experience buying from PC, when I visited the factory they were still selling only through dealers, and DW wanted something roomier than any of their models at the time.
For manufacturers who sell factory direct only, the "factory to you" price or "sale price" is often the beginning and end of price negotiation. Anything else you likely get might be coming out of the sales person's pocket, and how likely is that? If the factory does not sell through dealers, I don't know that a "suggested list price" makes any sense, except to make you think you are getting a discount by not going through a dealer.
Depending on where they are in their season, and backlog on orders, that factory direct price may change through the model year.
In most cases (again, I don't know about PC) a manufacturer in the "factory-direct" business does not build inventory to sell. This also hold costs down, no financing inventory. You come in, specify what you want, they put a price on it. If you agree to pay, they schedule your build. May be a few weeks, but at the top of the RV factory-direct scale (e.g. Newell) a build could be several months to a year.
I know BornFree as an exception, they build some non-custom inventory, but they also sell through a small number of dealers, treated as regional factory showrooms.