Sounds good. Do you remember the address?
The Apollo Hotel sauna is also worth a shot, though it's not as economical. between 350 and 400 for one girl, mainly depending on the time of day.
Apollo Hotel
132 Wuyi Zhong Lu
0591-83055555
In Chinese, it's:
阿波罗大酒店 (ā bō luَ)
福州市五一中路132号