My personal favourite is Luncheon meat.
At this time of the year it can be deadly. Not just fishing with cubes of it...also use a straw or a big pen to make pelleted luncheon meat.
I often use luncheon meat pellets when fishing for carp. You can make these any size you want and also the fish can easily suck em in.
You can dust the meat with groundbait if you like to change the flavours... i luv it
Many species will take this bait..if the little ones attack it try putting a larger lump or pellet on.
Sweetcorn is good as it can be coloured or flavoured. But many carp are wary of this stuff as its been fished with for so many years.. AKA the yellow peril..
Maggots...You can catch basically anything on them from gudgeon,minnow to carp and bream,..
Bread....
paste is cheap to make yourself..also if you catch a good fish on your home made paste its more rewarding..
Peas and beans also cheap..never fished with them but i have heard they can be great..