PLC Controller

[Lampshade]

That looks pretty interesting, and would actually be pretty fun to set up. But after adding up all the parts you need, board, clock, IO, relays,LED's etc. I think the logo is still a far cheaper system. The big drawback is having to pick up relays for switching, the logo contacts are good for up to 10A each, so that'd power 1200W of lighting.
I picked up my logo for $50 shipped, with the software included. I already had the programming cable, but they are new for $40 usually... but i've seen them under $20 on EBay. i'm either going to butcher a laptop charger for the power supply, or use a power supply out of an old computer, i only need 1A at 12V-24V, so both are far overpowered, giving me extra capability for addons. I got a thermocouple+transmitter for $20 off eBay(notice a trend?), and other than that, its all set up.

I do like the idea with the Arduino, VERY custumizable, and with the C++ programming, it wouldn't be hard to make a nice PC program to monitor everything.

Maybe i should buy a bunch of LOGO's and start selling custom tank PLC setups, that could be the ticket to a much bigger tank