I built a T4.2 that way, but it isn't worth it unless you have a bunch of parts already. I had ~1/3 of the truck (most importantly, I was able to source hubs, drive shafts, differential, chassis and won gift certificates that got me a body and steering rack) so I was able to save ~$150 compared to buying the truck off the shelf. The expense comes in hardware. I ordered a full screw kit instead of trying to piece together what I needed from individual screw sizes.