How are the first 2 "too complicated and expensive"? They look dead simple compared to 90% of the bases out there today. I don't have a fancy degree but It doesn't add up for me
The top graphics would do fine using sublimation on a sintered base. In general, it's extruded bases that are harder because the graphics can't be sublimated with digital printing. Die-cutting is independent of base material; it's just "something you can do". I don't, because while the bold color is nice the possibility of the die-cut coming loose isn't worth the effect to me.
The first two are definitely not good die-cut candidates. #1 COULD be done on extruded w/ a silkscreen - it's only what, 2 colors? #2 would need sublimated or, alternately silkscreened with halftones. But either would do fine on a higher end model with a sintered base.
As for the proposed "paper first" workflow, this depends greatly on what your design is, and also your equipment. If you have a Cintiq, paper isn't "necessary" unless you just happen to like it. If your art is collage, or shape and composition-driven like these, straight to Illustrator works just fine. As an aside, only one of Echelon's graphics was begun on paper (the "tools" being Wacom and Illustrator), and they worked out OK. The "SuperCarrier" did actually start as a sketch, but that was more to do with when I had the idea than because it was needed.
Anyway - nice work; they look clean.