For a desk i recommend Ikea which sells a solid steel model that's affordable.
I think it's called a Frederick.
I have an older model and it will probably last a lifetime.
I haved moved 3 times with it no problems try doing that with a particle board desk once i guarantee you'll have damage and i hate those cam lock things.
For a chair i would recommend you shop for them in person.
I'm a taller person and alot of chairs aren't designed for tall people.