Should Live Avatar API integration be hard and costly

We don't have the internal skills and have had to contract a developer to assist with implementing our (interactive) Live Avatar through API. The Avatar has been working well as an HTML embed for last couple of years, but I'm told it will perform even better with API. The contractor has undertaken a 'discovery' and already expended most of my $10K budget and is now telling me it will cost another $20K to do the embed into our WordPress website. I don't understand why is should be so costly. Any insights?