i3 processor or 128 GB SSD it would be worth it probably! But still, for me it wouldn't be low cost. But in the other hand, I do not live in US.
And I confess, I am not familiar with how popular is System76 and similar machines.
Although, I will say. For 200 euros I get Atom netbook from my local shop, with 50-100 dollar investment I can update to meet your current specs(ram+ssd). So Only difference I see, is that you have ubuntu preloaded. But you do not have screen included.
I think it would be good offer if I would get full deal within 349. Screen, where the PC is built in, keyboard and mouse. It should be hassle free for any grandmom for her internet machine.
Nevertheless, I wish you good luck. You have become further than most of us, making real difference. I can only talk, you really did something :)