Actually, I think you have that wrong. The cost of a 128GB SSD is closer to $80-$140 than $250 these days. I just checked on Newegg and those are the prices I found.
I didn't see this earlier. You're right. I was going mostly by memory and I didn't adjust for the time passed since the last time I read about it. I did google it and the 1st result is, ironically, newegg with a 128GB for $250, but it's sold out so it's likely old.
That doesn't change the fact that they are much more expensive than HDDs though still.
That's why I didn't spend much time researching this and verifying the prices. That post was less about the exact prices than the discrepancy between hard disk drives and solid state drives.