Those beams, and similar ones are pretty common. Most commercial lumber yards carry them. Architects and engineers love them, as opposed to natural timbers, because they are more predictable for figuring spans, etc. Some are called "micro lams".
Be careful when you remove large amounts of bearing walls. It can be done, but a qualified structural engineer should be hired, in addition to your architect. Even WITH approved engineers plans, I have seen goofs that your contractor needs to consider. You probably will need new and stronger footings for the posts that the loads get transferred to; You need to CAREFULLY study the wind shear forces and make sure you have enough lateral bracing. I have seen engineers restructure a house with only "static" loads, i.e.; everything was held up, but it had no lateral strength and a 20 mph wind almost knocked down a 3 story house as the bearing walls were being removed. The bearing walls had wind bracing in them. If it ends up being WIDE open, with no walls to put in your wind bracing, then you might have to have specially made steel connectors for your posts and beams and for the bottom of your posts, etc. to insure that the lateral forces can be checked through them.