those are still not dirt cheap. If we focus just on generics, every drug that I've ever been prescribed that is available as a generic cost a lot more here, at a Thai pharmacy, than what it would have cost at a Publix supermarket pharmacy in the US.
maybe for drugs that are still on patent but generic meds located though apps like GoodRx in the US are almost always cheaper than at Thai pharmacies, often by a lot.
I'd still put together a will to make sure that her right to the money (and any other assets you mightvhave in Thsiland at the time if your passibg) is unambiguous. I don't think that my wife would remain calm and well enough composed to immediately start draining bank accounts when she learned of my passing, so having some means of the money eventually getting to her on its own would be key.
The fully legal way would be to draft a Thai will leaving her the money. Or if you trust her implicitly you could put the money in an account jointly registered with her Having her drain an account registered only to you upon your passing with an ATM card or with the Bangkok Bank might work but it might also get her in trouble since if she's not your wife she ordinarily wouldn't have any right to your money.