Most mixes don’t need organ meats, no. If they do, it’s just liver, usually. The directions will tell you if you do, so don’t worry.
Also, many grocery stores will break packages for you, as well as cut up or grind just about anything. So say if you only want 4oz of liver, but they only a have a single 1lb pack, all you have to do it ask the butcher for a smaller portion.
You can also freeze just about anything you buy, and pack it up into separate smaller portions that’ll get used in one go, rather than using it all at once.
Btw, beef heart is a favorite at my house, and it’s CHEAP! Might be something to look into to keep costs down.
