I just remembered what could be a get out of jail free card on the transfomers. Low
voltage garden lighting is all the rage these days, and luckily for us, it uses 12 volt globes
etc. If you use a garden ighting transformers (or more likely transfromers for 4 50 watters), then the 240 wiring is all done for you. My Jaycar catalogue tells me that a 105
watt indoor (ie. not weather resistant in any way) 12 volt
transformer can be had for $39.95. (Though that might have changed by now - check their website & hunt around for them.)
I wouldn't think that two fans per side would be needed, perhaps ship could check this theory, but if you had single fan each side, set such that one blew in and the other out, the depending on the box volume
etc, you should be OK. You could probably use 12 volt computer fans and run them off the transfomer - I would suggest that whilst for load balancing you should stick one on each
transformer, it is probably better to put them bpoth on the same one so they operate as a pair. They'll only draw a couple of watts each, but it will depend on the actual fans you get as to whether you need to (and can safely) slightly overload the
transformer or not. Now I've just remembered that you'll need a bridge rectifier or the like here so the fans get the DC they need rather than AC. A slight
bit of filtration wouldn't go astray here either. Happy to give (and work out) the required details if need be.
I agree with Ship, given that you have said you'd like to stay away from 240 wiring, if the above solution doesn't work, find your nearest
sparky to ask.
With a pair of transformers, you could then put a
switch in series with each lamp and that would give you the basic
level of control you wanted. If you wanted remote control, use relays on them and the equivalent of analog lighting control - 1 control
wire per lamp, I'll give you more detail on this if you want it. I THINK that it is possible to use 240 dimmers on low
voltage AC (which is what you get out of those trasfomers), but given I am perceiving , and I am sorry if I have gotten this wrong, that you aren't terribly confident at the moment, and so I recommend that you just stay with a
switch in the 12 volt supply to each lamp - use a minimum 5 amp rated
switch at at least 12 v - So a 5 amp 125 volt
switch will handle it no problems. Doing it this way will allow you to add in dimmers or the like at a later date when you are more confident to do so.