Many people who look for home plans on www.theplancollection.com are being their own general contractor.  As a general contractor, I realize that some people just like torture and punishment.  For those people I know that one of your first hurdles will be finding a good/reasonable engineer.  Most building inspectors will require that your home plan be engineered to meet your local seismic requirements etc.  However, not all engineers are the same.  Some charge a lot more money than others, and some charge less, but over engineer your plan.  When they over do that, the cost to accommodate the engineering, can far out weigh the engineering fees. 

So how can you find out who the good engineers are?  Well, there are a few places to find information.  The Parade of Homes in your area often has a list of subcontractors and engineers in their parade magazine.  Also, your city building inspector can offer a lot of advice.  Simply ask him for a few names of local engineers who specialize in residential engineering.  He will also be able to give you some names for other sub contractors you will need.

Good Luck