I know you said you wanted a window, but you also stated that you wanted room to grow.
Here are a couple of cases that are decent, inexpensive and provide ample space for the inevitable growth.... the 901 excessively so.
Window kits are easy to install with the proper tools, and adds to the DIY pride.
In all honesty these are kinda like "modders cases" as they have great potential. Take a look around the modding forum for the likes of kennymeister, he did a great job on his 901B.