A VPS is much better yes - if you can afford it. For lightweight bots these little devices make for a very cheap and efficient dedicated server that you can just hook-up to your router and forget, that said, if you're not familiar with linux or need something with more power then an old desktop or laptop pc is much easier to use. Your home pc might be switched on all the time anyway - but having a dedicated box is much better if you want to become familiar with using remote equipment, have a shared pc, want a wired connection, etc
I got my pogoplug back out of the box and fired it up the other day, had a play around with it. I put my current live C bot on it for fun - turned out to be a bit expensive, not sure whether it was a subtle hardware difference, slower network, or random chance. Anyway, the novelty quickly wore off and it's back in its box now !