I agree with phamENG, unfortunately in my area they go for less than half a full design fee however. Almost everyone of these I have done has been a bust, hence why I price accordingly and get few of these now days. It's crazy that they expect our fee to be so little compared to the PEMB design fee which is usually at least triple your design fee. I had one where I was hired to design the foundation and a connector building between PEMB's and ended up having to design their wall system, elements attached to the PEMB, redesign foundations multiple times and then I found out their fee compared to mine and made a point to price these as normal buildings hence forth or write my proposals in such a way that I exclude redesigns of foundations, exclude designing their wall systems or attached elements, etc.
The best way to price these is look at the time it will take, add a multiplier (usually takes longer than we all estimate) and go with that number.