Wouldn't that data be encrypted? And wouldn't it be stored redundantly?

I don't know the answers I haven't looked much into Sia but I would hope so! (for them and their investors)

By the way cheap is relative, don't look at the price of a coin but look at the market capitalization. A very cheap coin with a huge market cap has less potential to grow than an expensive coin with low market cap (all other things being the same)