it will depend on the altcoin you are trading. right now $10,000 is going to give you 1.179BTC and with that amount you can affect the price of at least a hundred different altcoins, possibly more. these altcoins that i am talking about have small volumes since nobody trades them anymore so you can place big buy walls, manipulate the market and a lot of other tactics to pump and dump them.
but if you try to do anything in a bigger market your 1.179BTC will be nothing in something like litecoin for example because they have a much bigger market.
that is why it is becoming harder and harder to manipulate bitcoin because bitcoin is the only thing that is growing for real.
Exactly! You may never be called a Bitcoin whale (to even join the Bitcoin Club you should have 21 BTC, regardless of the amount) but if you look even on a big exchange like Bittrex, you see coins with daily trading volumes between 1 to 10 BTC. Even with 1 BTC you could trade back and forth several times a day and make the price go crazy.
Manipulation is real in altcoins, as you said.