that price range is tough. if you want to go corals/ reef, one of the biggest expenses is the initial light purchase. However some continuing expenses come from the electric bill and replacing the bulbs. T-5 is a good new option as the bulbs only need to be replaced every 2 years not every 6 months, and produce very little heat, and you wont need a chiller. your tank being 3' deep is 36". T-5 is not recommended for reef tanks deep than 30", but if you get a decent setup you can get some low light stuff or just keep things off the bottom 6" of the tank. T-5 is a great choice economically as they produce great amounts of light. However, they are only worthwhile if the bulbs are individually reflected. for this reason, i recommend either Tek or Aquactinics. these are both great brands, unfortunately for your size tank, i doubt you will find a light rig for 300 dollars. Do yourself a favor and either wait and save up for the RIGHT light system, or dont upgrade. why waste money on something that is not right for your tank, that you will end up replacing in a few months?