I would compare this to pricing a car without any photos, really impossible to do.
What is the NADA price for this?
2018 is pretty new...mabye try building a boat on the Bennington website with what that boat has, and see the MSRP on it. Granted Bennington does not make a G series any longer, I would build the LX (closest thing to the G) and see the MSRP...take 15% off that price (seems to be conservative estimate on what people are paying under MSRP when ordering from Bennington, not showroom floor,) and you can get a ball park.
Remember, we are at the point that building and ordering custom will place people into summer at this point. So ready to go boats that are used or on dealer floors will be at a much higher premium and therefore it becomes a sellers market
Factor in condition of boat, maintenance, warranty..is it the 5 year or the 10 year they offer now?