I recently acquired a 5 gal tank......If I where to do a nano-reef, how much would the equipment cost be? a rough estimate is fine.

Filter: $20-$30
Power head:$20-$30
Heater:$10-$20
Lighting: (this is going to depend on the type of lighting you want. you may want to upgrade to a 10 gal. because you will be able to find a fixture that will fit easier)

Keep in mind that you probably won't want to go with the cheapest lighting system out there, because the kind of lighting you have is going to limit what kind of corals you can put. I would definately stay away from MH with a tank that small though...your temp would be all over the place. Also you are going to want a filter that is rated higher than five gallon (in your case you might want a filter made for a 20-30 gallon aquarium). Or you could just not use an extra filter and just rely on biological filtration, this option is becoming more and more popular for nano tanks.

Over all, with a lighting system your equipment will probably cost around $120. Again, the price will change depending on what type of lighting you get, but this will give you a loose estimate.

Hope this helps
Kaiden

Kaiden is right, that is up or depend to the lightning you want.. So the better the lightning the higher the rate..

Exactly.