My first was scratchbuilt (honest). Over 30 years ago now, it was built from some scraps from my uncle's rocketry supplies. Body tube was an old Estes engine shipping tube (light blue), a leftover balsa nose cone and balsa fins cut to roughly emulate the Alpha pattern (done by eye, looking at the Estes catalog). Engine mount consisted of tons of masking tape wrapped around the engine (friction fit for a non min diameter tube). Shock cord was a length of cotton twine, crepe-paper streamer, and an eye hook I scrounged from my Dad's collection of miscellaneous screws. It was rougly Alpha-esque, although a lot cruder. Paint was was whatever enamel found on the garage shelf. (Did I mention walking to school was uphill both ways?)
First factory kit was an Estes Mark II. Lost it on its second flight. Turned me off to kits for while. I could scratch build for a fraction of the cost, saving my pennies (literally) for engines. I can remember that firing three (ABC) motors in any given session was an "expensive" day of flying. All my launch hardware was scratch built, and that tendency continues to this day, only buying kits where they are classics or are otherwise unique.