I agree with you, but only to a certain extent.
You shouldn't just randomly buy the cheapest coins. There's a very good chance that they're cheap for a reason!
The key is to look closely at what the team behind the coin is doing. What is the economic theory behind the coin? Is it a true currency that is likely to be used as a medium of exchange, or is it a useless token that was just used to raise startup capital? What is the team like - distributed or centralized? Does the makeup of the team fit the project?
If you can find a coin that you truly believe in, with an experienced team that makes sense, and it has a low market cap, then go for it. I did this with VTC and am very happy right now. My favorite small coin right now is ZEN.
But of course, I'm not offering any investment advice. Just my opinion. Good luck to you!