The Verilux HappyLight Lucent VT22 is a good SAD light but is held back from being a great SAD light due to a couple of design issues.
The HappyLight Compact Energy Lamp is one of the cheaper SAD lights on the market, but is made by the reliable chaps (and chapesses) at Verilux. It only provides 2,500 lux of light, but is compact and portable and the light tone is lovely.
This Verilux HappyLight offers a variety of light intensities up to a maximum of 7,500 lux and is small and weighs next to nothing. It is also made by Verilux who have a strong brand name when it comes to SAD lights.
The Verilux Happylight Personal is very inexpensive indeed and it comes from a reputable brand name. It provides 5,000 lux and is small and well made.
The HappyLight Deluxe has a huge surface light area and a nice tone of light, but it is also quite pricey.