Just to compare and contract, our voting precinct is at a nice Protestant megachurch in our area which has over 3000 congregants, cost less than $1 million to build (including the land), includes a state of the art sound system, cafe, youth center but (so far as I know), no armory for storing weapons, munitions and bomb making materials.
I know land is a lot more expensive in the DC area, but not 100x more.