Simply buy a full-fare economy ticket from the airline of your choice, if everything works out as you plan, you might not need it and can cancel for a full refund anytime
thanks for your insight, so the disadvantage of applying from abroad - health insurance requirement - is compensated by not having to bring fresh money to Thailand?
about the depositing of money... Many sources say it has to be fresh money, coming from abroad. Obviously I can't use my bank to exchange EUR as the bank rates are very low. Will a Superrich receipt be sufficient to prove the foreign origin?