What should I put in my homemade hamster food? I can't afford store bought hamster food so Ill make?

You can go ahead and add these:

1. Pellets and seeds. (if your hamsters seems to be eating only the fatty seeds and pellets, eliminate those and give him/her the non-fatty pellets and seeds.)
2. It's also healthy for them if they eat a bit of lettuce or carrot or apple, etc. if they finish their food, give it to them, if they do not finish their food and you give it to them they will think that they will not have to eat and continue to live off of treats.

you could research other foods you could add to their plate, but these will be the base of all their foods. Good luck! :)