Alright here is what I did for much less than a protein skimmer is worth
It's a nice 10 gallon planted tank with 2 cories,a guppy and 2 danios....
Here is a breakdown of what I bought :
Whisper 10(shoulda gotten the 20 my mom bought it for me ) $20
Airpump (had it for hydroponics) like $10
Airstone 12 inches long in the back of the tank $4
Gravel $10 but don't buy the gravel if you want more than 10 pounds buy Ph inert pebble sized river rock works good for me buffers the Ph well from my 6.2 Ph water
Air tubing $2
Lighting 2 under the cabenit lights like $10 or so for both from wallmart CFLs are better
The hood material I bought this flourscent grid for my 55 gallon had some left used it for the hood placed the lights ontop . $10 for alot of the grid material
Plants were in a trade I say $20 or so maybe for a well planted tank but very/well planted tanks are messy when not cleaned alot.
Nitrite,Nitrate,Ph and Hardness test like a 4 in one from ebay by jungle labs for $10
Doy the tank a 10 gallon from wallmart for $10 or a 20 for like $25. (I had an extra one)
So say $100-$110 for a very nice 10 to 20 gallon setup you could shave money by buying river rock for 10 cents a pound.not buying a test kit and ya I spent less than listed with some stuff I had on hand. Now a reef setup is like expensive mondo expensive but if you have enough initial funds then your set and some funds for monthly things.
Here is a very very basic list of the chilling costs that have been keeping me at bay for a reef :
Protein skimmer $100-120
Canestir Filter $60 to $100
Lighting $150 to $250
Tank $30 or so for a 20 gallon
Power head $15 to $20
Salt like Instant Ocean $30 to $40
Some way for Specific Gravity (Salinity) $8 (Hygrometer) to $40 (refractometer)
Test kit $30 or so to like $40
Live Sand $20 for a 20 pound bag
LR the butt clencher in costs
Like $120 for 40 pounds 1 to 1.5 pounds a gallon
HEater $30 or so there other things but thats the money important stuff..