Backing makes sense, if for no other reason than it inspires tenacity in the bowyer. Sometimes you need a good dose of "it ain't over till I says it's over" to get through some of the early, or more challenging, projects.
But it's also important for a budding selfbowyer to aggressively seek source material. Be resourceful, dilligent, creative and don't give up until you have a nice pile (5 or 10) pieces you can fall back upon for future projects. If it's any guidance, being in the game 8 or 9 years and having slowed to 5 or 6 bows a year, I probably have enough wood products for 100 projects, and I'm not exaggerating. This aspect of the game is nearly as fun as the building actually, at least for me. Chances are there's sources for bow wood all around you. A $20 bow saw, an axe maybe, hell even just a little hatchet, find yourself a site where they are clearing land for development in your area and, shazame, bow wood galore. You gotta get that primitive man's point of view, tunnel vision, as if your next meal depended upon it.