I've just started in the stockmarket and set up an account with InteractiveBrokers.co.uk last week.
If you are over 21 years old, you'll need $10,000 minimum to start with them ($3,000 if you are under 21). This is the equivelant to 7,800 euro.
You are charged a minimum of $10 per month commissions, i.e. if you run up commissions of $6 for the month, you will still be charged an additional $4 to meet the minimum (the minimum is $3 if you're under 25).
To start with them, I set up an account and purchased equal amounts of 16 different shares. They are all U.S. based shares - you can lodge Euros via AIB at a charge of 75 cents and change it to US dollars on their website at VERY good commission rates.
My plan is to put money in every month at a cost of 75 cents via AIB. I am going to start buying European shares (4 euro commission per trade). This means I can buy two different shares per month and will be charged $10 commission.
My 16 purchases of US shares cost 2 euro Foreign Exchange commission and 12.45 euro dealing commissions - a total of 14.45 euro.
To do the same via AIB would have cost me at least 512 euro in dealing commissions and I wouldn't have got as good a rate when transferring my Euros to Dollars