So you can discover Dandár, Király, Lukács, Paskál, Rudas, as well as the popular Gellért and Széchenyi thermal baths for free via these handly links:
 

• Dandár Thermal Spa Baths

• St. Gellért Thermal Bath and Swimming Pool

• Király Spa Bath

• St. Lukács Thermal Bath and Swimming Pool

• Paskál Thermal Bath and Lido

• Rudas Spa Baths and Swimming Pool

• Széchenyi Thermal Spa and Swimming Pool

Source: 
budapestinfo.hu