Roma tomatoes go on sale here periodically. In fact the last couple of weeks, they have been on sale for 99 cents a pound. When they are on sale, I buy them in bulk. Once home, I wash them and dice them. There really is no reason to remove the skin or worry about the seeds. Then I divide them into 1 3/4 cup sections (which is the amount contained in a 15 oz. can) and freeze them to use as needed.
This is not only frugal, but it gives me to complete control over the quality of tomatoes and their packaging. I use 2 cup glass Pyrex containers to freeze my diced tomatoes, but you can also use sandwich bags if you don't have freezer safe containers available.