Join Date: Nov 2011
Location: SF East Bay Area
I would start with a single 48" Current USA LED+ or Finnex Ray 2, both within your budget. I would then wait a month or so to decide if you really want to add a second LED fixture for more light (my prediction is that you will anyways).
Or you can bite the bullet and get a 4 x t5ho quality fixture that allows you to turn on 2 bulbs at a time.
To answer your last question, my personal philosophy is " buy cheap, buy twice".
Edit: 55g is one of the most common tanks. Look up people's journals to see what their experiences are with different set ups.
Courtesy * Integrity * Perseverance * Indominable Spirit * and Self Control
Tenets of TKD