Craigslist. I.E- Right now in my state there is a 55 gallon and stand for sale at $50.00. Too bad I don't have room otherwise into the savings account I would dive.
Go with the Base rock idea. i spent 100 bucks and got fifty pounds of base and free shipping. Then spent about $60.00 for three pounds of manado live rock and that included shipping.
Do your research and don't impulsively buy. I dropped $100.00 on a sea clone only to find out it really isn't that great of a skimmer.
DIY projects also save you money I.E. a petco stand with canopy for a fifty five gallon would run you around 250 and I built myself a stand for forty and have left over wood enough for a canopy. also built my own sump/fuge for about 40 as well.
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