I think it is your budget that is limiting what your kitchen is like, especially in Bangkok. I pay more than double that amount in Hua Hin, but I have a pool, so it's not a great comparison.
Mine has an inside kitchen with cooker, hob, microwave and dishwasher, as well as an outside kitchen with a washing machine. Even the condo I stayed in at first had a hob and washing machine.
A Thai visa agent can't guarantee you a visa for the USA. All they can do is organise the proof that you have to provide anyway, so you would be wasting your money. They can't bribe someone in the usa to guarantee success.
Get your proof (lots of it) organised, cover everything requested by immigration, with each document numbered and a list of all the documents. Then submit it yourself. If your proof is badly organised or missing, the chances are they will reject the application.