To answer the comment regarding refurbishing the plates...
I just checked my contract. The guarantee only guarantees that the plate will be there. It doesn't mention anything about guaranteeing the condition of the plate. As a matter of fact, it says that the sponsor may not request maintenance on the plate and that they "shall have no control over the placement, appearance, or maintenance of" the plate.
In other words, if you sponsored one, you paid your fee to have the thing engraved one time on a metal plate and placed on the monolith. After that, there were no services guaranteed or implied.
Interesting...but it makes sense for...what was it? $35?