I made my own flexible partition with a plexiglass window. I don't need a walk through door because I got the wide passenger seat.
Anyway, imagine a curtain made of two-inch-thick lined cotton batting insulation with a rectangle cut in it and fitted with a plexiglass window. It drapes behind the front seats and accommodates any kind of tilting I do with the driver's seat.
Provides very nice thermal and acoustic insulation and cost far less than $100.
I seamed together two of these (
http://www.homedepot.com/p/UltraTou...ot-Water-Heater-Blanket-60301-48752/202710039) for the curtain and then lined it with cloth and cut to shape. Oh, and added the plexiglass window.