Sorry, too many threads on too many forums, after a day or two I can't recall what was said in what page of what thread, the one your looking at is the tinyurl link to the $1100 hp still right, thats the only one I see.

Have you considered the option of haveing one built by a local pc shop, this way any support you need is right there. If you do want name brand there are local shops that will do those too, I used to work for one, we did mostly government but sold to smaller businesses too. Some of those small local companies will donate time and/or parts to organizations such as yours, I did a couple donation jobs myself.