andrew-d:
Why does it appear the bootloader is in more than one memory location?
My guess here is that you tried a number of different things (eg. install bootloader from the IDE, install from avrdude) and they failed in different ways (the ways being the incorrect address).
As for the rest, congratulations on sticking with the problem solving. Many people would give up. I suspect that the cheap programmers are not necessarily fully tested on every board, and who wants to advertise that their board doesn't work with some things?
Probably the AVRISP will work simply because it comes from the manufacturers and they - if no-one else - has a vested interest in being able to program their own chips.