Not strictly true. Developers, both for H/W and S/W, made it clear that BC on the 360 relied on emulation. ...Original BC conception focused on getting the likes of Halo2 running and no more. The limitations of BC were always openly declared. From minus day one, BC games were listed on xbox.com and to this day they are still listed on there. Buyers know exactly what games work and what ones don't. At no point was BC used to sell systems, in fact all advertising relating to the 360 refers purely to playing 360 games on the 360 console.
Meh, I just buy used if theres really no other choice (like, you wont be able to find a new wondermega nowadays...) but a lastgen console? c'mon! I cant buy a used one...