HOT DOG
It looks like every thing has gone up in price, and the value of our money has gone down. The money you have to spend will be to the value of where you spend it. If you are going to a shack, resturant, or jump into taxi's tuk-tuks every day ,which we know all know that chage over the top then it will not last you long. Take a bus and keep every piece of change you have to pay the bus fares, if you give them a note, 90% of the time you do not get change.
Look around, before you decide which shack on the beach to make your daily base. There are many, many, local resturants, that do not have big screen tvs, they do not have someone imitating elvis, or neil diamond, they are cheaper to use. Haggle, and haggle and haggle, if you do not get the price you want, walk away, but at least you will know how far down the scale of payment they are willing to go too. So the next shop you go to for the same item, you know the price to start haggling at. A couple of years ago 600 pound a month would make you a millionaire over in Goa. But this time make sure you check out prices before you buy anything at all. If this money is just for entertainment and food and drink, then it will more than last.