Definition of an SR-22 from the Car Insurance Term page:

SR-22 - A form which must be filed by the insurance company stating that auto liability insurance is in effect for a particular individual. Required when insurance is provided to an individual who was in an accident or was convicted of a traffic offense and was unable to show financial responsibility.

Each state has different variations of this form and requirements. The SR-22 requirement should not directly affect the ability to obtain financing. Financing is unrelated to the necessity or obligation of the financial responsibility laws of a state.

We have many related questions to help you better understand an SR-22. 

Comment Update: You ask how much it costs. Typically, it is an additional $15 to $25 filing fee. Because you have to purchase coverage levels that are required by the financial responsibility laws of the state, you may see an increase cost over what you are used to paying. This is because you are purchasing more coverage than what you previously had.