If there’s one thing I absolutely must stress, it’s that the single most important factor in putting solid mass on your body is being in a state of caloric surplus. What that means is eating a decent amount more calories per day than you are using up. These surplus calories are what your body will use to create new tissue, ideally muscle (albeit some of this will inevitably come from fat, regardless of how slowly or carefully you go about it). You can go for a conservative surplus of about 250 calories, or aim for around 1000 if you want to be aggressive about it.
Another thing you’ll notice with the following recommendations is that most of these foods will be generally higher in fat than most of what you’ll see out there. This is because there seems to be a mainstream fear of fat intake for some unfounded reason. The important thing to consider is that unless you are overweight, a smoker, or have any other high risk factors for cardiovascular disease, having a moderate amount of saturated fat in your diet will do you no harm.
Now that we’ve got that out of the way, lets get started…
Probably the cheapest source of protein on this list, eggs make a very solid ‘muscle-building’ food. Eggs are packed with a variety of other important micro nutrients, and even a half-decent amount of omega-3’s. They can even be incorporated into your diet in a variety of circumstances, be it scrambled or in the recipe for a protein pancake. A lot of people seem to fear whole eggs and go for egg whites. The thing with is is that is it a great deal less economical and defeats the purpose of trying to save money in the first place. And just as a side-note, the whole deal about the cholesterol in egg yolks being a health risk is dis-proven bro-science, so do not worry.
Red meat is an awesome protein source and can be adapted to pretty much any meal when paired with a carb (rice, pasta, potatoes). A lot of people try and go for the very lean varieties (97% and 99%) but these tend to be extremely pricey. You could always purchase the 90/10 variety and simply filter out the oil that seeps out of the meat during the cooking process, which significantly lowers the fat content of the end product.
You might have heard chicken breast recommended over and over again due to it consisting almost entirely of protein. However, chicken thighs are a great deal cheaper, have just as much protein with a slightly higher proportion of fat, and most importantly, taste a hell of a lot better!
This is probably the most effective ‘vegetarian’ option of a protein source, being almost on par with eggs for price/gram of protein. In addition, beans are packed with nutrients and plenty of fibre to contribute to both your overall health, and aid in digestion of all that food your going to be eating while trying to gain weight.
There really isn't much to say here. Its cheap and it's easy to prepare. It goes with nearly everything. Just throw a bunch in the rice cooker in the morning and keep it on warm, and you’ve got your carbs sorted for the entire rest of the day!
A little bit pricier than rice per gram of carbohydrate, but has the huge advantages of reduced satiety in general (meaning you can eat more of it without getting too full and feeling bloated, allowing you to get in more calories throughout the day), as well as having more fibre and protein!
Almost every “bro's” favorite breakfast, these are packed with carbs and fibre, and you can add pretty much anything you want to them. Protein powder, fruits, a bit of brown sugar. You can really get creative with oats if you want to!
Probably the holy grail for getting the most bang-for-your-buck calories-wise. Its also packed with pretty much every nutrient you need for making maximal gains during your bulk. If you want to get really extreme with it, you can ad some protein powder to it and make your own homemade Mass Gainer.
Before we finish this up you need to understand that there isn't any magic about any of these foods. They are simply the most cost-efficient ways of getting the calories and nutrients you need to maximize your progress during your mass gaining phase with the smallest possible impact in your wallet!