Shop around and look for good deaks either on craigslist or in the newspaper.
You can always find 10-20g setups for a few bucks, most of the time they have a heater and or pumps etc.....
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Live Sand, make sure its aragonite based calcium based, you can save yourself a lot of money by purchasing dry sand thats not live. Take a small amount of sand, pour some vinegar over it, if it bubbles and fizes, then it's a calcium based sand and good to use, depending on your location, sometimes the local super-hardware stores carry 50lb bags for just a few bucks, just make sure it calcium based, not silica based. Use this dead sand in your tank and then get handful of LS from a friend or sometimes the LFS will sell you some, use this handfull of LS to seed the sand....The reason you want calcium based sand is that it has a buffering action on your pH, the silica sand doesn't.
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Check around for deals on real LR, the DIY stuff looks good and it's cheap to make but in no way will it ever offer the biological surface area or buffering action of real live rock. If you have to splurge on one single item in the tank, save up for the real LR, even if you only have enough for 50lbs, you can always add more later....Hope this helps