I'm curious as to whether others have "guidelines" as to what goes into your collection?

Do you buy one camera a month? Year? Or when you come across them?

Do you only buy cameras you can restore? Or do you buy things only in mint condition?

Or do you require that it be useable?

Do you keep multiples, or multiple models of a certain camera?

How do you balance the financial end of things? Never pay more than "x" amount, or "x" amount per month? Do you build a budget for collecting?