Turkish Airlines offers cheap return flights from Dublin to Shanghai from £386.There is no specific travel period for this fare. But sale ends on March 31st, 2013.
The fare rule allows a stopover for only €30 in Istanbul. So if you like, you can spend some days in Istanbul, before you continue your travel to Shanghai.
If you wish to stay a few days in Istanbul, you have to use the multi destination search form. Please check the pictures below.
Please check Skyscanner.com for a connection flight from your home airport to Dublin.