It depends on what other options you have, your power costs, and other factors I can't speak to.
In MY situation, I didn't consider it worth buying past about the first batch (that I couldn't get into) as I have other options that I think will earn me more money for the same level of investment.
In YOUR situation, I can't say because I don't KNOW your situation or your preferences.
Well, my situation is, i am a UK Resident and my electricity rates is around 0.24 usd per kwh. Currently I am sharing electricity bill with 3 other family members so i don't have the burden of paying it all myself.