Forgot to mention water... it's best to make water your drink of choice, but don't forget that coffee, unsweetened tea and the water in your food, also counts toward your intake.
Honestly, it's less expensive to eat healthy than it is to buy processed foods that are not healthy. A head of lettuce, some tomatoes, cucumbers, etc to make a salad costs less than a family sized bag of chips. A loaf of whole grain bread, peanut butter and jelly costs less than pop tarts. A box of oatmeal costs less than a box of sugary cereal. A lot of fresh veggies cost less than their canned counterparts.
Also be sure to check the frozen foods.. often my store has frozen veggies on sale at Buy One, Get One price, so I can stock my freezer. If you opt for varieties that are not packed in butter or cheese/cream sauces, that are just as healthy as fresh.
Buy chicken, fish or other meats when they're on sale and wrap the pieces individually, to stock your freezer. Whenever you need a single piece, you can just get it from the freezer.
For every processed food you would buy, there's a fresh or nearly fresh alternative. Shop around the outside edges of the store... that's where you'll find the produce, meats, dairy, etc.
Dress up plain veggies with healthy oils, lemon juice, vinegar, herbs and/or spices.
I've always drank lots of water. It's very good for your skin.
Healthy food can be inexpensive. For example, buy a bag of dried beans. Fat free. Lots of protein. Cost under $1.00. Last 5-6 meals.
Weight in kg x 30 milliliters if you go by the metric system. For me that makes 1800 ml water (1, 8l). Not so hard if you have a bottle of 500ml next to you all day :)
Good luck (right now I didn't have access to the US oz etc but I hope you find a way.