That all depends on what type of diving you will be doing and what the conditions are. In order to stay around your budget I will give you a couple of suggestions, but honestly I would consider waiting until your budget allows for a little more room. LIghts are expensive but at night, and undewater, they are alot more than just cool things to have. They are essential equipment.
Primary: Pelican Nemo, Princenton Tec c4 or c8
Back Up: Mini q40, or Princeton Tec Torrent
I own a pelican nemo but compared to the HID and eLED lights out there it's not even in the same ball park. The Mini q40 Screams! its a great back up light and you can find them for around $38.00.
My best suggestion would be to look around for an Underwater Kenitcs Light Cannon. I just bought one for my girlfriend on sale for $170.00. She also uses the q40 as her back up.
What ever primary you end up going with try to look for eLED or LED lights there color and intesity are much better than standard lights, however they do cost more.