You can start as small as $2-3 by trading small alts and flip them for substantial profits.
The only thing you should keep in mind while dealing/trading in cryptocurrencies is that you should bet only what you can afford to lose.
Good luck!
Not too low because it has no benefit to start from $2-3, better not to start trading. It is not a joke. The amount should be enough which can give you some profit. You dont need to invest big amount at start but gradually you should increase your investment as you gain knowledge and experience about crypto trading. There is no limit for crypto trading in start.