I've been 4 or 5 times, and never paid anywhere near £7 a pint.
On average it was 3.50 Euro - 4 Euro a pint (£3.20-£3.70), the rate is obviously not helping.
Where are you staying?
On arrival at the airport, the shuttle bus to the centre is about the best bet. It takes about 20 minutes, and is about 5 euros each. The buses run every 15-20 mins.
If you've never been before, I recommend the Guinness factory. Ok it's not everyones cup of tea, but I enjoyed it and i've been in twice. On a clear day, you get a superb view of the city from the bar right at the very top of the building. This is where you enjoy your free pint.
The Luas (tram) will get you there from the centre of dublin.
Temple bar is generally more expensive, but there are plenty of bars over the liffey that will be in some cases upto 1 euro a pint cheaper.
The Auld Dubliner on Temple Bar was a favourite of mine.
You'l know when you have pretty much arrived in the centre. Look out for 'The Spike' !