I don't want to just pile on the negativity, because this hobby is A BLAST, but there are tons and tons of factors that go into successfully keeping a reef tank. Even after you have the tank set up, you aren't done spending money on it, you have to plan to spend a decent amount of your time and money just to keep everything alive. Buying RODI water (no tap water), saltwater (unless you mix your own - but then you have to buy the salt), food (specific to what your livestock is), test kits (5-8 of those are NECESSARY and run about $15-25 EACH), supplements, etc...
I really think you will enjoy this hobby. I was in just about the same boat as you when I got started. 20g tall tank, live rock, live sand, a couple of cheap powerheads, a $75 light fixture, and livestock. I skimped on some quality though, and took a bunch of shortcuts, and paid for it 10 fold with headaches. Ended up spending somewhere around $500 before I was able to get the tank somewhat stable.
With that said... I would urge you to consider what a couple of the previous posters said: Save your money until you can afford to buy a complete used setup.
In the mean time, you have come to a great place to LEARN! There are tons of threads to read and tons of information that a beginner hobbyist NEEDS to know before they jump in with both feet and get in over their head. READ READ READ! Ask questions! Again, it's an expensive hobby, so learn from others' mistakes and it will save you boatloads of $$$.
Good Luck!