I say put the 6.5s you already have up front in the stock location(you'll need to make a plate) for now. Remove the rear factory door speakers. Save up some more money for a set of 6.5" components and a nice amp to power them.
'01 Escape XLT V6 on S100
CDT Audio/Ascendant Audio/Rockford/JBL/Knukonceptz setup
'00 SE Sport ATX