How much will it cost to build a bed room not connected to the house like it guest house but not a house just a bedroom in the philippines?

so my girlfriend wants to build a bedroom separate from the house I guess out of cinder blocks. do you know how much will it cost maybe not sure on the size with a like feet and inch but here a photo to give the size she say she did like
Update: i guess she still want it out of cinder books but she did like this pic of a room trying to get some kind of idea also i am not the one paying for this she is
Update 2: this will be built in the Philippines not USA
Update 3: there a tiny house that even smaller then the one i posted
Update 4: one last thing the property is private the ower let my gf fmaily live there as her father is the care taker and he harvest the coconuts then the owner sell it and her father get a % of the sale so it not like there be many pepole to see it
Update 5: But does ann one know how much it is going to cost to build some thing like that
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