It's best to have fun at your own expense. Gulangyu Island is the main place in Xiamen. You can also visit Xiamen University, which is very beautiful.
I suggest staying at Gulangyu International Youth Hostel in Xiamen. Is this their website /ls.php? id=39
You can live in a quadruple room. This guest house has an elegant environment, and Chen He has just filmed there. Read their posts:
/bbs/viewthread.php? tid=5 105