Mark,
I know what you mean. I've always loved making tackle items myself, my local tackle shops also used to have the mandatory jam jars full of Peacock/crow quills, sarcandas reeds and part built balsa bodies e.t.c.
Some of the materials I've found easy to collect or buy, and useful for home made floats, are, Norfolk reeds, swan/goose quills, elder pith and balsa dowel.
Nowadays I mainly only make my own piking floats, like Chris B said earlier they cost pence to make and can be made in literally minutes.
I also used to build my own specimen rods. When I began there were huge gaps in the specialist rod market and most serious anglers advocated building your own purpose built rods. I used to use hollow glass North Western blanks, funnily enough one of my local shops still has a pile of them in a dusty corner. I keep meaning to grab a few before it's too late, there are one or two applications I'd like to have a go at, but I don't really fancy splashing out on new rods for it. There's a couple of blanks that would be ideal for the job in that dusty corner, or at least there were last time I looked.
Regards Chris