These were the first two planes off the line and they were significantly heavier and performed much worse than most of the other 380s. Singapore Airlines got rid of them for that very reason, while still taking delivery of new 380s. This is why they weren't attractive to any buyers.

Note one of the early SQ 380s is now operated by Portuguese charter airline Hi Fly.

I wouldn't count of the first two's demise being indicative of secondary value of all aircrafts of the type.