It depends on where your home is. Over the next few months, I expect we'll see people in Europe (who often have electricity costs above $0.20/kWh and high VAT) switch to datacenters built from the ground up for hosting bitcoin miners (like the one I'm building, which should charge less than $90/kW/mo or $0.125/kWh). However, if you already live in a place with cheap electricity (like West Virginia, $0.06/kWh), and if you don't have to rent a place just for your miners, then running at home could be a bit more economical as long as you don't place a high price on having a quiet and cool home. You can't get that many machines into your own home, though, so the bulk of the network hashrate (and the eventual hashrate equilibrium, I expect) will be running at around $0.125/kWh.

Immersion cooling will, unfortunately, have high capital costs. I would be surprised if they can get the capital costs down to a level where it can compete with air cooling for commodity hardware, especially if you have good datacenter design and a cool climate.