...I have put down a deposit on a baby unweaned yellow sided turquoise green cheek conure and it loves to bite me and I make sure not to react but he keeps on and it's hard biting too...
Just wanted to chime in, here, on the "no reaction" method of dealing with bites. I don't know why this technique gets so much play, but I'm hoping to save you from an unnecessary investment of pain and blood for the purpose of bite pressure training your bird.
Remember that when birds nip or bite, they are most often communicating with you. They might be letting you know that they're afraid, or annoyed. Or they might even be playing. Thing is, they may not understand how much pressure is too much pressure. So why meet their attempts at interaction with stoic silence?
You definitely want to keep your reaction controlled, of course. After all, they might find an animated reaction amusing and actually seek to trigger a repeat performance for their own amusement. So you should tell them "No," in a firm, yet even, voice. If they clamp down, grip the beak just above the point with the thumb and index finger of your free hand (ie the one not being used as a nibble toy) and with a
gently twisting motion pull the beak away from your ailing flesh.
There should be no question in his/her mind that you find the current level of bite pressure unacceptable. Subsequent infractions should lead to a repeated "No" and a timeout of around 15 minutes. (Not feasible in a bird store, I know. This is more for when you get them home.) Wash, rinse, repeat.
The method Lullx mentioned is also very effective with repeated use. Again, the goal is to bite pressure train your bird with minimum pain and bloodshed.

Distraction, deflection and timeouts are all viable tools for that purpose.
Good luck on your decision, and make sure to post pics once you make your final choice!