Actually, the way to properly do this is to sell raffle tickets.

Maybe make each raffle tickets $300…

The grand prize would be you are income tax exempt for 4 years
The 1st place prize would be you are income tax exempt for 3 years
The 2nd place prize would be you are income tax exempt for 2 years
The 3rd place prize would be you are income tax exempt for 1 year

The can also sell sponsorship tiles. For $100 each, you can design a ceramic tile with your name, etc, and that tile will be placed along the Wall after it is completed