i agree with cb750 cafe racer fan.
start with what you have. if you want to paint, with the right prep rattle can can go a long way. also, if you want to add custom touches, like lights, you don't have to stay motorcycle specific. i bought some generic cab marker lights (the beehive style) from the NAPA store for about 8 bucks each, I think, and also a 4. in round S/T/T light ,with a license plate light lens, for about he same. it doesn't have to be expensive to work. plus, if i screw something up or drop the bike, i don't have to feel too bad about it.
the other thing i think about...how were cafe racers (or hot rods) built back in the day? i can't imagine they had the access to aftermarket parts that we do. they worked with what they had, or what they could find. i have to remind myself i am not working with a rare and priceless example of motorcycle history. parts are available, and most anything i can break, can be fixed. buy what you can, when you can.
there is a wealth of info out there, just go for it.
later,
ryan