Here's how majority of ID companies work.

You consult them for ID for your home and they come up with a quote that looks affordable and they tell you we can help you manage your renovation as well as we know the design and have relationships with material suppliers to ensure the ID comes out exactly how it was envisioned.

Bad thing, a friend of mine hired an ID consultant and he wanted to put in a wooden table into his house and the ID consultant said no... design does not allow for ANY wooden finish furniture... talk about paying someone to tell you how to live, plus the glass table recommended comes at a cost of RM13k.

Hahahaha... so how do ID companies make their money anyway? Well, the design fee is one but because its usually discounted for owners who take up their project management service, that cost is sufficient to cover manpower time cost + small profit margin.

Majority of their income comes from managing your project. Yes you've paid them a fee to cover that together with the design charges but do you think they're not getting a cut from all the materials selected bought, etc...? Of course they are otherwise profitability is a problem.

I would suggest comparing costs for ID and non-ID executed projects to find out the differences in prices.