Can an American Football player use Soccer cleats in a game if he or she cannot afford regular football cleats?

Depends on the playing level. When my son was 10 and 11, he wore the same cleats for soccer and football. Now he's a little older, stronger, faster and needs the extra support and protection offered by football cleats. Soccer cleats don't protect or support the ankles.

I thought soccer players wore ballet slippers?

Most likely. I'm sure different leagues have different rules, but like football cleats, soccer cleats are plastic and not very sharp. I have personally bought soccer cleats for my son because they were the best looking cleats on the shelf. That said, however, if you play on artificial turf, you will need a different cleat than if you play on grass and you need to consider what type of traction the cleat pattern is likely to give. Some soccer cleats have cleats that are too broad, in my opinion, to be good in football. In football, you definitely want a cleat that sinks into the turf well.

RE: Bad Pookie's post - if the player is older and stronger, than you may need to consider the high-top style football cleat if they have weaker ankles, but I never wore them much, even in HS or as an adult playing rec-league stuff. I think most pros use tape on their ankles rather than high-tops.

correct me if i'm wrong here, but in professional football (nfl), dont all players wear the exact same cleats?