Buying/commissioning a costume is not cheating. If you've never tackled making these kinds of things before, I'd suggest different Link and Zelda outfits for your debut. The DS and N64 game designs are easier projects to make, and they will give you much needed experience. Even Skyward Sword has easier designs to make. The TP outfits won't seem quite so overwhelming after a practice set of cosplays.
Check out the Zelda forum on this site for specific advice. Or the General Construction forums for singular questions (i.e. pattern/material for this dress, how to make this sword, which wigs, etc.)
Otherwise you can commission the TP outfits, although it will cost you guys a tidy sum.
Just my two cents...