The only reason stock 128k Macs are collectable is because it was the 1st one made, they didn't sell that well so they are a little rare, and anybody who purchased one would have upgraded it just to make it usefull.

Its like people who spend tons of cash for the rare Atari 2600 carts, you know the ones that sucked so bad you could not give them away. Rarity might command some cash to fanatic collectors, but it does not mean the machine is so great from a users standpoint.