try watari (i think so..) near amara hotel....i think u pay less
than 20 and u eat all the tempura u can...
one of those shophouses...forgot the street name...
or u can go genki sushi at holiday plaza at JB. it is not buffet
style, but u buy a set and u get the set, plus chawanmushi, miso
soup, fruit, and other stuff...less than 10 bucks (SGD).