I believe you can use a regular window. For example, I am putting a window in my passenger slider, but I wanted the AMA sliding window and I wanted it to open in the front. AMA confirmed I can use a driver side window in the passenger slider. So I think that could go the other way too.
You didn't say what kind of window but Motion Windows makes sliders for either side. Thats what I have. The screen areas are rearward on both sides. Door window space is same on 136", 159", and 159"Ext.
I know that I am reviving an older thread but for future reference:
If you want a stock type window you can simply purchase one from a local auto glass shop. You do not have to have them install it (although their prices are usually reasonable). I cut the hole and installed a passenger side window and the cost at a local glass installer was 130.00 USD for just the window. I did ask about a drivers side and it was also available but I chose not to put one in (it was not a slider but I am sure they could have gotten me one).