Ay sis, sa Pangasinan usually around 800-1500 pesos depende sa clinic at kung private or public hospital, pero mas mura talaga sa government centers na parang 300-500 lang if available, a few of my mum friends dito nagpa-ultrasound sa Lingayen Medical Center at Provincial Hospital and sulit na ang presyo! At 4 months ka na, great timing for your detailed scan, kaya go ahead with it para peace of mind mo lang.