Are you trying to find a budget carrier or an unscheduled airline (aka charter)?

All budget airlines offer less service than full-service airlines. That's why they are able to charge less. They don't transfer luggage, even between their own flights, etc. And they aren't good about informing passengers of schedule changes, cancellations, etc, in advance of the passenger arriving at the airport. They don't offer pre-assigned seating , their baggage allowances are low, etc. If that bothers you, you'll need to purchase a ticket with a full-service carrier such as Thai or Singapore Air. They do have promotional fares from time to time.

All that said, there are quite a number of posters here who have flown Air Asia. Some have been driven crazy by schedule changes, etc, others have felt it was the best airfare bargain they've found. Tiger and Jet Star have both received ok reviews, subject to the caveats above about budget airlines.

So it really depends on you. How important is service and convenience vs. cost?

Just an update to Kathie's post. Thai Air Asia does now offer assigned seating with premium seats, at the front of the plane, and the regular seats. You can also pre purchase how many pieces of luggage you will have with you as well as you can pre purchase meals if that is what you want. How ever they don't fly directly from Bangkok to Singapore so you must buy two tickets!

Singapore Airline is offering some very cheap seats from Bangkok so have have you check with their web site? Their price for economy are as low as Thai Baht 5,895 nett for a return flight.

Hanuman! Good call on Singapore Airlines. The equivalent of £80 on the date we want. It's probably worth the extra to go scheduled instead of budget. I'd only looked up the fares on price-comparison websites and they were much, much higher. That'll teach me to check the airline's own website too! Thanks to all.

If it was me I would save a considerable amount and fly with Air Asia. Depending how far you book in advance and the day, the cost could be as low as £28 plus baggage cost, meals and pre seating charges. They have 4 flights a day non stop. Or Tiger Air has great rates also.