You could maybe cut that cost by making one of those lights a motion detector, but I think that a full time florescent bulb is going to be cheaper to run than turning an incandescent or mercury vapor off and on.I've got a dusk to dawn florescent security light that is 14 watts.

It is possible to get lights rated "non insulation-contact", but for those, you have to build a box around the fixture up in the attic if you ever want to add insulation.Also, if you get can lights that take incandescent or compact fluorescent bulbs, install the correct bulbs - usually reflector bulbs. 

Replacing incandescent lighting with CFL's could also save you some money.

Thomas Edison created the incandescent light bulb and it took 10,000 tries.

LED lights and CFLs like draw much less power than incandescent lights do. 100 amp service is more about central A/C and electric dryers than anything else.

HomeDepot carries a line that are $20 - $30 per light (less if you have volume discounts), are as bright as two incandescent 60w bulbs - but only consume 4w, and {best of all} there are no light bulbs to be changed or stolen {light bulb theft is a surprisingly big thing in our student rentals}.

We purchase the specialty bulbs (appliance, fan, porch bug light, etc.) and incandescents.

The way I see it, "pretty" gets tenants in, and "inexpensive bills" keeps them in.Here's my quick list: .8 gpf toilet(Niagara Stealth at Home Depot,) Niagara Sava Spa 1.75 gpm showerhead, Watersense-labeled faucets, and LED bulbs from either Lighting Ever(LE) or Hyperikon(go for the 2700 K color temperature, and usually 9 watts or so is equivalent to a 60 watt incandescent.)

LED produce less heat than regular incandescent lights, but are very heat sensitive.  

Incandescent vs halogen vs LED?