This should include an initial meeting, back and forth and an output of plans drawn up by an architect.
We got quotes from 3 different architects/designers for an addition to a 1700 sqft Cape Cod style home and the cost was approximately ~$6,000. That’s basically an all-in cost for meetings, someone taking measurements, revisions and ultimately a blueprint that could be shopped to builders. The addition would cost ~$200k. So an estimate as a percent of total cost of the renovation is around 3% for the architect plans.