Frozen veggies are better (USUALLY cheaper), because you can store them for long term, eat what you want and put back the rest......meaning you dont have to cook it all at once like you would with canned, and fresh because they perish quickly. Fresh is best though if you plan to eat them right away or to cook with in recipes.
How much money you spend on healthy food really depends on the store you buy it in, and what exactly you consider to be healthy. For example, while low sugar/low calorie/low fat ice cream is better than regular...........ice cream is still bad and is not healthy, therefore you save money and freezer space by not buying it at all, and when you do have a craving.......go to dairy queen or where ever and get some. Then when its' gone it's gone and you havent eaten a whole tub of ice cream and you dont feel guilty (I have done this many a times myself when depressed so I know
) Another example is chips. They make low fat, fat free, and baked ones, which granted are better than regular, but they still arent healthy, so again you save money by not buying them at all.
I dont mean to make you mad with my post, just to give you a different perspective. Good luck with eating healthy and your diet