30 Gallon Tall need Light/Reef

I just purchased a used tank with existing live rock. It is a tall 30 gallon. During the transport the light was damaged beyond repair. I must now replace it and am looking for an inexpensive solution to begin with. I am new to all this and do not want to sink too much money into it until I am sure I can handle it. My long term goals is a tank with corals and less than a handful of fish (maybe a starfish).For now I would just like to keep my live rock and tank healthy. There may be some coral hiding in there (mushrooms I think and there is one other one that I don't know if it is alive or dead). I'm currently letting the tank cycle and read that light is not needed for the process. I do need to order soon though so I have it ready.
Also on a side note do most people have any type of heating in their tanks. The person I bought it from said you really do not need to do much to maintain the temperature. I'm a little frightened because I try to save money on utilities and my home is kept at 65 in the winter when I am not home during the day and 78 in the summer. Will this affect my tank.
Thanks for any input.
-Tyschire