I just mine for fun and to see how things perform.
So I mine LTC on my Linux desktop which is a Haswell i5 with a Geforce GTX770 at ~ 200kHash/s. Not really impressive but pleasant for me as a hobby.
I've looked into the power costs and I'm paying roughly $0.28 / kW/h.
I'm looking at some options for a dedicated mining rig but am not yet ready to choose.
I don't really want to invest hundreds into new hardware. So some cheaper 5/6 series Radeon cards combined with a AMD Sempron 145 based system and a motherboard with a minimum of three PCI-e slots would seem to be the best option for me.
But again. I'm still not certain. I just want to mine with a bit more power but don't want to loose to much
on power.
TFK