the refugium is a good place to house a skimmer and macro algae for EASY nutrient export, it makes life easier......................
as far as lights, getting a used t5 set up will likely only be a bit more than other lights used for just fish..
also live rock doesnt need good lighting
when or if you go to corals start with softies,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,they are the easiest