I'm looking for an inexpensive beam mount rack for light commuting use. Something made of aluminum, or an alu/plastic combo. Around the $20 to $25 price range, a load capacity of 9 kilo/20 lbs. minimum and, preferably, round edges so I can mount a light on it.

I checked out the one from Zefal which is thermoplastic with aluminum support tubes, it is quite nice and feels sturdy but is too short. I also checked out Topeak but they are in a different (higher) quality and price range, which is unnecessary for my use (they do look very nice however ). Also tried BBB's Postrack, reasonable quality but didn't feel as sturdy as the Zefal. Plus it's practically impossible to mount a light on it.

Anyone have any suggestions? Thanks in advance!