If i were to change my 10 gallon freshwater tank into a nano reef would it cost a lot?

More then freshwater. live rock ~$200, lighting ~150, powerheads ~$50. So around $400-500 dollars.

Thats probably a little excessive for a 10 gallon nano. Lighting will be your biggest investment but for a 10 gallon you can probably get by with $75-$100 for lights.
Live rock will run you $3-$6 a pound depending on the source and you will want approx 1 pound per gallon if not a little more. You will also need some sand for the substrate. A couple Koralia Evolutions nano 425 powerheads at $25-$30 apiece and you have most of what you need. You probably already have a heater and maintenance equipment but you will want a hydrometer or refractometer to test the salinity, a saltwater master test kit to test the cycle parameters and eventually calcium and alkalinity test kits. Use only RO/DI water or distilled water and a good salt mix and you increase your chances or a successful reef system.

Add all that up and you're pretty close to my estimate. Just saying............

$100 for lighting, $60 for live rock and $60 for powerheads is not $400-$500. It $220 in my estimation. Add another $50 for a test kit and hydrometer and $20 for salt and you're still at more like $300 and thats worst case. You can probably find some if not everything on Craigslist or from local reefers for less.

Do i need special lighting for a FOWRL tank?

To keep the life on the rock going it takes higher than normal wattage or intensity as compared to a freshwater tank. On a 10 gallon you could get by with something like a 96 watt powerquad Power Compact, a 70 watt metal halide, a couple T-5's or maybe a Ecoxotic Panoram LED strip. I have two Panoramas over a 16 gallon bowfront reef with many corals in it as well as an anemone and all do well.

When I did my 10 gallon I bought live sand for 15, live rock for 25 got 12 pounds, the power compacts for that size would be about 40-50 depending on where you go. There's a small T5 set up for 50 by coralife. a powerhead that does about 200gph would be around 20 buck. whats that 15+25+50+20 and you can probably be ok with the same HOB filter you use now with 10% waterchanges. So anything else would be salt. It's not 500... Someone doesn't know how to shop around

haha.. you guys... i've got my 75 gal up and running (without lights so far) for 150 bucks... lighting will be about 300 when i build it with LEDs.. For a 10 gallon? here goes:

you'll need at least 10 lbs of live rock... the lfs has it for 6$lb.. you can find it as cheap as 1$/lb from local reefers. Live sand? get regular sand and a handful of live sand from a local reefer... so 10 lbs of sand.. what, 10 bucks? powerheads? you'll need at least 200 gph, so 20-30 bucks for a new koralia, cheaper for a used one or different brand. Lighting? a FOWLR will only require about 30 watts if you keep NO coral at all (so a 26 watt 6500K CFL). if you want coral and plan to use those nasty fluorescents or MH, then 60 watts for ok growth. If you use LEDs (and build your own) you'll need about 6-10 3 watt Cree LEDs (3-5 blue, 3-5 white) 50 bucks and a 30$ power supply as well as a small heatsink from home depot or an old amplifier that doest work. Then some testing supplies (just an API reef master and test strips work well enough for me) and salt (17$ for a bag enough for a 55 gal). So 90 bucks on the low end and 230ish on the high end. I'd shoot for the LEDs if you could, they wont need to be replaced for 10 or so years.. unlike the MH and FL lights, ever 6 months to a year for those. If you want to know more, feel free to ask!

I've got a 12 gallon nano and I've got a bit more than a $400 investment in this tank. You can definitely go cheaper, and definitely go more expensive. I've switched entirely to led's which are a bit pricey but are worth the investment long-term. I am very pleased with them. Hope this helps

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Namaste

A reef aquarium or reef tank is an marine aquarium that prominently displays live corals and other marine invertebrates as well as fish that play a role in maintaining the coral reef environment. A reef aquarium requires appropriately intense lighting, turbulent water movement, and more stable water chemistry than fish-only marine aquaria, and careful consideration is given to which reef animals are appropriate and compatible with each other.For a long time now it has been seen as a good thing not to load up one’s tank with copius amounts of liverock. People have been asking you to remember some swimming space for the fish and room for corals to grow. Most of us nano reefkeepers know all to well that adding the ‘recommended’ amount of rock to a tank can quickly dash your reef aquarium dreams and turn them into ‘tank- o- rock’ realities.

Thanks