Bush and Sauder are two RTA brands that use various types and thicknesses of particle/"engineered" board, and some of their more premium offerings are fairly sturdy.
I actually just purchased such a desk and hutch from Bush (staples online), one of their new Office lines of furniture, and it's extremely sturdy. Still definitely going to get banged up fairly easy if it has to be moved frequently through tight spaces (at least the desktop is melamine treated all around, though I wish all the faces on the front were treated too, but alas, I didn't want to spend upwards of $800 for solid veneer desks).
I was looking all over the place,and couldn't find a good affordable desk setup, one that also fit my needs, which were fairly picky I might add: Needed ample storage room, and that ruled out all the good affordable solid wood desks, and also had specific maximum dimensions that ruled out most of the desks I kind of drooled over.