How Much Liquid Assets needed?

A good gauge of liquid assets required depends on the down payment requirement.

Down Liquid
50% 2-3 times purchase price or more depending on neighborhood
40% 1 1/2-2
30-33% 1 times
25% 2-3 years of carrying charges (mortgage+maintenance) or 1-1/2 times purchase price in some specific buildings (Sutton Place, lower Fifth)
20% 1-2 years

The more prestigious the neighborhood the higher the requirements, usually. Ask the listing broker if they know. They will say there is no set formula, but they should have an idea based on past sales.