TubeBuddy is a good, cheap alternative. The free version is decent but relatively limited. You can get their Pro tier (~$3) if you're on a tight budget, as it offers a good amount of SEO tools. But the best option would be the Legend tier (~$20) which provides video ranking across YouTube and Google and opportunities (personalized recommendations for keywords). I've heard good things about vidIQ as well, but I haven't tested it out personally. Hope it helps!