I really feel you on this, it can be quite worrying when the polyclinic refers them out after the assessment. I don't have the exact figures for NUH speech therapy on hand, but I'd suggest calling the NUH appointment line directly to ask about the subsidised rates, especially if your son is a Singapore citizen as the subsidy can make quite a difference. My girl had a similar referral a while back and the admin staff were quite helpful when I just called to ask upfront before the first visit. Hope your son's sessions go smoothly and he starts to open up more soon.