At first glance, I doubt those fixtures would be suitable for growing most freshwater plants. 1W LEDs are generally just not very powerful - especially at depths over 12" or so. The PAR ratings I have seen around the net for most 1W LEDs are abysmal. On a 56 gallon tank, if you want an LED fixture, your best bet would be to build one... you are not going to find a COTS fixture that suits your budget and is suitable for growing plants.
T5HO would be your best lighting solution with that budget, imo. As Talvari pointed out, fishneedit make a decent fixture for about the best price you can find.