Autonumber set to integer with the identity property, use decimal for the other
Create table table_name(
id [int] IDENTITY (1, 1) NOT NULL,
price [decimal](10, 2) NULL)
)
Actually the number of places allowed in the decimal can be adjusted based on how big you think the number will get. This one contains 10 places, 2 of which are to the right of the decimal point. The automunber will start with one and increment by one each time.
By the way ID is not a really good name for a field. Use PriceID or something similar. Later on (when you have 50 tables) you will want to know which table this ID relates to, so it is better to start with a unique name now.