We have a 228 Jayco which had a storage door (non window) for the bottom bunk. We wanted a window there so all three kids could get some airflow(the new window has a slider, screened opening). We had the dealer quote us on the window. It's approximately 32" wide X 18" high and was about $600 installed. If you have a local Jayco dealer or are buying from a dealer check with them first. They should be able to quote you for what you want. Ryan.
Me, the wife, three kids (Son, 9 yr old & twin 5 yr old girls)
2013 Ford F-150 FX4 5.0L 4X4 3.55
2012 Jayco Jayfeather 228