Is there any particular reason why you are shopping "new" for these parts (solarbotics, sparkfun) instead of "surplus" (all electronics, electronic goldmine, etc)? Certain parts I understand would be difficult or impossible to source from surplus (like fairly recent microcontrollers, for instance), but others (like the gearmotors, L298, etc) can likely be picked up for a much lower price. Do you not trust surplus, or are you approaching this from a different angle where you want to be able to purchase components manufactured "today" that won't run out "tomorrow"?