According to the chart over at the DD-WRT web site this model needs a power supply that has 5 volts DC and is capable of 2 amps.
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dd-wrt.com/wiki/index.ph ··· s#BelkinSo just about any 5 volt DC power supply that is rated at 2 amps or greater will work just fine with the unit as long as it has a compatible plug on it.
Time to look into the junk box or visit a decent electronics supply house. Other places to check are Salvation Army, Good Will, or a used computer shop.