Hi guyes.I really need to know how much Dex need a lucky Hunter/Archer.

It will require a bit of reading, but your answer can be found in here. If I remember correctly, 300 dex is what you should aim for at the least though.

It is not possible to answer your question with the information you've given.

100
200
150
800
400
300
500
1200

^ These are all possible answers.

We need to know your current level, your goal level, your budget, and whether you have a PvE or PvP focus.