starting project management business targeting cosmetic renovations

Hi guys,

Looking at creating a project management business purely for cosmetic renovations. Basically targeting investors who are time poor, and ensuring the renovation gets done for the cheapest price, high quality and the shortest amount of time possible.

The situation:

I am currently a foreman for a commercial construction company and I am a carpenter by trade. I am studying at night to get my builders licence.

What I would like to do:
 
Is offer a service to a client where they tell me exactly what they want done for the renovation. I break all theses tasks into the relevant trades. Then maybe obtain half a dozen quotes from each of the trades and pick the cheapest from each trade. Put together a price and offer it to the client.

Charging fees:

My fee would be worked out by estimating 5 percent of the projected profit assumption………… And I stress assumption. that for every 3 dollars spent 5 dollars in equity can be gained. Therefore if 30 grand was spent, expected equity gain to be 50 grand i would charge 5 percent of 20 grand.  Something like that, I dunno whether Im being to expensive or too cheap……

All of the chosen trades invoices will be sent directly to the client.

Ill be moving to queensland in 6 months and i read that to undertake any works over 11 000 dollars in queensland requires a builders licence. This is what grabbed my attention as everyone says spend as rule of thumb 10 percent of the purchase cost when the the average house is a around 450 grand that means a cosmetic reno is going to cost roughly 45 k therefore ruling out a lot of people in queensland if the 11 thousand dollar rule is correct.

The thing that really attracts me to this idea is the general simplicity, as only general cosmetic works are being undertaken. And coming from a trade and management background I would have the necesary skills to project manage and help out people who dont have enough time to manage tradies while they are at work. 

Your advice and views are greatly appreciated and if anyone else is doing something similar it would be great to hear your thoughts!

thanks in advance