Bangkok-Dublin

see.......EMIRATES or ETIHAD airlines, both have daily direct flights from UAE.

Thai Airlines via LHR...

Try Ryanair.

In all seriousness you could use budget airlines to get back, but they don't tend to be much cheaper.

Example:-

Bangkok to Calcutta = Air Asia, from £43.
Calcutta to Delhi = Spice Jet or Indigo, from £54
Delhi to Sharjah = Air Arabia from £90
Sharjah to Istanbul = Air Arabia again, from £62
Istanbul to London Luton = Easyjet, from £31
London Luton to Dublin = Ryanair, from £17.

In theory therefore, you can get a flight from £297. But nailing that price would be very difficult and some of the layovers would be an absolute mother trucker, with no recompense if any of the flights along the way get delayed.

Still, would be fun to try...

Thanks all...Froggie..In all seriousness,that's a humorous suggestion.