Agree...The Alliance for the Separation of School & State has some good information.
The site you linked to certainly has a lot of detailed info, and I agree with the overall idea of parental choice through private education.
However, I have several serious concerns regarding the cost and funding info this site describes. For instance, it identifies the average tuition costs of private schools at $2,500-$3,000 in order to make its plan of wholly funding educational subsidies to the poor by charitable donations viable. However, they selectively only took the average tuition for religious schools (which are already subsidized by the affiliated churches) into consideration - the sectarian counterparts have tuition costs well over triple the working figure. Furthermore, unless the donations all go to a general pool that disburses the funds to all qualifying students to do what they wish with it, the parents will still not have real choice as they will be dependent on the wishes of the donating entities, i.e. if they want funding, they have to attend the favored school of the benefactor.
The only way I see that a private school system can replace the public one is if it can attain the goal of placing the choice of educational values in the hands of the parents without excluding any children because of economic limitations or religious/sectarian preference. This means that the source of financing tuition subsidies must be able to guarantee enough cash, and those contributing must be willing to fund educational choices they may not agree with. I fear an all voluntary contribution system will not be able to satisfy both of these requirements at the same time.
An unfortunate acronym that makes