I'm gonna run off some #s making some assumptions.
Some of them could go up or down depending upon your prefs.
OK, a quick and dirty appraisal. (all in THB)
Housing: 15K/mo Stick you in the Kata Beach Studio (In low season they do some pretty decent monthly deals) This is excellent location in heart of 2p2 land and <300m from nice beach. Walking distance to a bunch of restaurants.
note : pour nous se serait plus proche de 18K/mo pour une chouette maison/villa 4 ou 5 chambres. Ca reste quand même pas très cher pour un truc assez luxueux, avec services (femme de ménage)
Mais faudra rajouter les factures d'électricité, eau et internet. (je sais pas encore à combien on peut s'attendre, j'ai posé la question)
Transpo: 5K/mo. You gots to rent a motorbike if you want to stay in teh Phuket. (4K/mo for rental ~1K/mo on petrol) The petrol estimate is purposely VHigh becuase you are not coming here to sit in your room all day. You want to ride around and see paradise, like everyday)
Apparement indispensable d'avoir une moto/scooter pour faire les déplacement sur l'ile vu que y'a rien a portée de marche.
Foods: 10K/mo. This assumes ~330/day which is tight but doable. If you only ate at "Red Chair"(formerly "Guay Jab") which is a fast, good Thai restaurant like 100m walk from KBS, you'd be full of delicious Thai food at around 90THB/meal. The slack in the 330/day assumes your gonna want an occasional Farang meal like a Burger or pizza or pasta or whatnot. So you could prob splurge on that like 2-3 times a week at ~300/meal(farang food).
Apparement la bouffe est vrmt pas cher et super bonne, donc ca c'est un gros plus 
Going Out ~10K-30K. This really depends upon you and how often. GOing to the kata Night bazaar which a few of us for a few drinks/beers can bee 300-1K. GOing out in Patong can get expensive depending upon where you hit. Prob a decent assumption to expect to spend around _500/night on a low key chill some drinks night and at least 1K/night on a clubbing crushing Patong night. The best way to get value on big nights is to go with a group and bring your own bottles. Most clubs let you bring in your own bottles and charge a ridiculously small corkage fee that also includes mixers. Doing it this way is ridic cheaper than just buying single drinks.
Womenz No estimate available. Totally depends upon you.
Il parle de prostituées au cas ou qqun aurait pas compris..
Seeing stuff If you are here, you might as well do some one off trips like Phi Phi Island. 1 day trip there ~1.5K. Maybe a Full Moon Party if you are young and into beach raves with scandis and aussies. A 3 day trip there on the cheap would prob be ~10K.
C'est des dépenses extra mais que tu fais que 1 fois.
So adding up:
20K housing
5K Transpo
10K Food
10K going out (using low end of range)
---------------------------------
Monthly nut = 45KTHB ~ $1400
j'ai edit avec le prix de notre location plutot que celle qu'il propose.
Rajoute 5k pour des dépenses non prévues, ou genre des resto/sorties un peu plus cher que ce qu'il prévoit etc on arrive a 50.000 BTH ou ~1500$
I think you couldn't really go much lower on the food w/o cooking a ****on of your own meals which is silly when a great Thai meal is only 90THB.
Also, you need to add some more discretionary THBs on there esp for the unknownz like womenz.
Hope that helps.
Voilà
