Estimated price difference between buying now vs. end of season?

I'm looking to upgrade from my starter bike ('02 SV650), and to a 3-5 year old Bonneville T100. There are a number of valid options currently on sale from CL in my area (New England), and I'm sure that will continue to be the case. Just wondering, those who have more experience with CL buying/selling - how much cheaper might similar bikes be if I were to wait for the colder months? 10-20%? More? Less?

Just a ballpark, or previous experiences are good.