Hindi ko sure ng exact clinics sa Tondo/Sta. Mesa area, but I'd suggest calling around sa major hospitals like Jose Rizal Medical Center or asking your OB, usually they have a preferred ultrasound center na trusted nila and may package pricing pa para sa CAS. A few of us got ours done sa private imaging centers na malapit lang sa hospitals, and it ranged from around 3-5k depending kung comprehensive or basic lang, so it's good to ask around sa friends din or sa prenatal forums para makakuha ng referrals na tested na!