If you're riding in the city then the main goal is to be seen. Most bike shops offer compact front/rear light sets starting at about $20. In the pinch any light is better than no light and drug stores such as Walgreens and CVS offer low cost LED lamps starting at about $6, look for lights that easily mount on your bike or helmet.
Any bicyclist who crosses over the city line at night knows one thing--darkness. That blinky light on your front handlebar becomes almost useless. But trying to find a moderately priced light to see the potholes is difficult, expect to pay at least one dollar per lumen.
I found three resources on the internet that may help you find the right light. Candlepower Forums has a bike light database that includes lights that produce at least 80 lumens. It is an excellent start point to search for serious bike light manufacturers.
Even better is the Eddy's Bike Shop in Ohio website, they set up a darkroom and photographed the resulting beam from their stock of headlights, below are samples of two different lights.
40 - 50 Lumens ------------ 200 Lumens
And finally the Planet Bike Light Finder is a similar web page that features their own lights.
I should note that we are finding that only about 40% of the urban core riders are using lights at all, anecdotally that number plunges way down for working cyclists in the outer neighborhoods and suburbs. Getting everybody to use any grade of lighting at night could significantly reduce the number of bicyclists injuries and fatalities.