Do you realize that if this is done incorrectly you could A) Bleed to Death B) Die from infection?
DONT DONT DONT DO IT. There are large blood vessels and nerves in your tongue, and if you hit the wrong part you could cause massive bleeding and/or permanent nerve damage to your tongue. You have to go to a professional.
Wait to get it done until you can afford it. Just like with any piercing, you're risking A LOT doing it yourself. Think of it like getting a tattoo, would you rather save up money and get it done by an artist or go to some random person and have them possible mess it up and ruin it forever? Just save up the money, a tongue piercing isn't that expensive.
Firstly I have my tongue pierced and it was done proffessionaly. Today however earlier on to be exact I pierced my smiley myself. I had it done professional before, but this time short on cash and been wanting it redone for ages I decided to do it myself. Bought gas sterilized 1.2mm x 50mm 16g needle from ebay. My point however is I only did this as there are no veins or potential worrying spots that could cause serious harm. Its only a super thing layer of flap/webbing kinda thing. But with the tongue its thick and has loads of veins that if puntured will cause unstoppable bleeding which is a trip to a&e. Basically because there is so much that could go wrong in that area its a high risk!!! So piercings like that should always be done professionally. :)
I would not try this at home. If it gets infected you will have to go to the hospital. I have heard cases of peoples tongue getting infected and they have to have surgery to remove the piece or the entire tongue. I would not suggest this!!