It sounds like in Thailand he can get a larger place on/near the beach than he would be able to get in BA. The lifestyle change is pretty different, and in BA where inflation is high and you're not on a garantia a rent that starts at $800 bucks could find itself at $1000 within 1 year.
Generally speaking, unless you have a lot of luck, most of the tourist apartments will only give you a lease for 6 months, and then every 6 months they will either ask you to pay yet another round of commission fees and/or raise your rent yet again. The first time you sign the lease you can almost guarantee that they will ask for 1 month commission and 1 month deposit, and then your 6 months of rent (you may be able to negotiate to pay month by month)... but basically you're looking at $800 x 6 + $800 commission + $800 deposit = up to $6400 usd up front ($5600 rent and commis, $800 deposit) but only 6 mos of renting = $933 a month + $800 deposit. Comission is gone, deposit you can probably get back at the end of the contract.
So if $800 is really your ceiling, then you need a place that is $685 usd a month ($685 x 6 and a commiss = $4795 usd total, and then your $685 deposit that will hopefully be returned).
The problem with the 6 mos rentals is that it can be really hard to get out of paying these stupid comissions, so every 6mos you're actually paying 7 mos of rent. If you stay in one place for a while you can try and negotiate it with the agency, but they can be asses. And they are almost guaranteed to up your rent at the end of every 6 mos period.
On top of that, they will use the most ridiculous reasons to not return your deposit. A missing spoon, a broken glass, a chair that was already broken before you moved in, or some stain that you told them was there before and you can say goodbye to your deposit -- unless you have the time to spend about another month or more arguing with them to get it back. They will do anything possible to not give back any money.