You've come to the right place for help! As the finance department (a.k
.a. Mom) for 2 of the members here, I totally understand the budget issues. We started with a 90 gallon for my youngest son and all became hooked! Some input:
* we didn't buy live sand; bought good quality argonite instead and cycled
* we bought base rock, a few "show" pieces of live rock and cycled the tank (takes longer but saves lots)
*buy a good skimmer up front; we didn't and had to replace within 6 months because ours was crap (recommended by lfs
, listen to these guys instead)
unit was a great investment; oldest son bought ours on ebay for a good $
*probably don't need to worry about heater right now
*you can start out by just buying the couple test kits you'll need to cycle the tank (ammonia, nitrate, nitrite) or make friends with guy at lfs
and maybe they will test for free
*be patient! It took us about 6-8 weeks to get our tank properly cycled.
*we had basic compact lights to start; upgraded when $ allowed
By that time, you'll have more money saved. Initially you'll just add your cleaning crew. Have fun!