You better get a visa, you've already got here for 150days and done border bounce twice. Even if you fly out and in, you might not be allowed to get in the country or get a lot of questions about the purpose to be in thailand which is clearly not just for tourism..
there's a post on another thai visa group of a lady from Zimbabwe who bought a ticket before getting her visa (having a ticket is required). The visa was denied and it seems she bought a non refundable ticket which she has probably lost. This folk appears to be smarter so he will probably apply for his visa using the onward ticket as a proof. In the worst case his loss would be just 20bucks
lol, that's what everyone says in the states and in france and in germany and in spain and in italy and in china and in japan..... Immigrants is always the reason lol
if you have no visa 99.9% of the times the ground stuff will require you a proof that you are leaving the country in 30days otherwise they won't let you check-in. Airlines are very careful about this point cuz if the immigration won't let in the country, they are responsible to fly you out and cover the expenses ;)
you got 2 choices: 1) get a tourist visa (60days) at the local thai embassy. 2) get here on visa exempt and then apply for a 30days extension@1900baht. Remember that airlines will require you to show an outbound ticket out of the country within 30 days so you might need to buy an onward ticket