Alternative designs for a load bearing wall
You should balance the expected savings from a more optimal design with the cost of hiring an engineer to do an alternative design. 

Supposedly, the 10k includes their time to design the structure, build, including materials. 

An assumption here is that the majority of the cost is labour and design, neither of which you save on with a more economic design (moreover, more complex but economic designs might be more labour intensive). If this is the situation, just get other quotes for the design you like. 

If this assumption is wrong and the potential savings on materials is greater than the cost of an engineer, it might be worth getting an alternative design.