Oh no my cat has fleas I think..?

My cat has been scratching a lot and it's kinda weird. Like today me and my mom looked for them and all we saw was these specks that looked like pepper flakes. Last night I saw a bug that looked kinda like a flea. I was gonna pick it out of his fur and then it quick went under his fur. Any tips? We are gonna get some frontline plus. Any other cheap anti-flea stuff? We are pretty sure he has fleas.