When I came, 10 years ago, one-way ticket cost about $800. You could live in a template and eat rice... That is the cheapest way.
You have 6 years. In that time I would focus more on finding an income more than finding discounts.
Some younger people come here with the intention of working for a living. I think minimally skilled expats earn about $1000 - $1500 a month, teaching or scuba instructor... Those are pretty much the only two jobs you can do, unless you have some very unique skills (doctor specializing in something and you are recognized as the worlds best, they may let you practice your specialty - but I have not yet seen that).
$500/month gets you pretty good place in Bangkok near no transportation. 750 may get you a decent place near transportation.. Or ride a motorcycle... If you are ok with eating only rice you can probably survive on a dollar a day... Then everything additional costs more. I think you will find $1000-$1500 is enough to get by for awhile. You will have to choose, air conditioning or save for emergencies. You will not have enough money for both.
My advice to you.. Save every penny you can for the next 6 years and/or spend the 6 years finding a job that can be done remotely, or spend the next 5 years acquiring the skill you need to find a job that can be done remotely.
Craigslist and bahtsold.com are good sites to do some rental window shopping.
Over the past weekend I had to re-stamp in (border bounce).. I went to Cambodia, stayed for about 3 minutes and came back.
Thai immigration (and likely the neighbors) are happy to welcome tourists who come to spend time and money, then leave. That sounds like that is what you are doing... I don't think you will have any problems.
If you get pulled aside at an immigration check-point. Make sure to complement the culture, people and food. Some people get this part twisted. If you become argumentative the Immigration Officer can deny you entry and be a pain in the ass... If you are polite and respectful the Immigration Officer is all to happy to grant you permission to stay (and spend money). No kidding, people do get this point twisted.
That's what I thought. I thought my bank Bangkok Bank. required Wise to make a special desgination that the funds come from overseas, otherwise I couldn't use those funds for things like buying property or proof of funds/income.
I don't know it, but I have a friend from the US who tells me it's better to get the retirement visa within the Thailand. This is because of insurance. Just something for you to look out for.
I have used Agents bunches of times and I have no complaints. However, I think it's better to not use an agent if possible. I concern that once you start with the agent you'll be stuck using the agent.
Another problem I have had is where I open my bank account. For many of your interactions with your bank, you will have to go to the branch where you opened the account. If you open an account in Bangkok then move to Samui, you may have to travel to Bangkok to get your banking paperwork... There may be ways around this but do you really want the hassle.
I would recommend coming on an METV or DTV, figure out where you want to live for the next five years and start working on the requirements to moving here (seasoned bank account, purchase/lease condo, etc etc).