I think the MX is $10 more.
Yep I believe you'd have to look at the stat's and compare at newegg to see the differences.
Were the previous prices the caused by massive profit margins?
What was sacrificed to cause such a big price drop (e.g. write cycle endurance)?
I'm suspicious of any product that, for no obvious reason, suddenly costs 50% less.
Will these drives start failing after a few months of use?
In 2008 when I bought my first SSD (65GB for $265) there were only OCZ and Intel on the market. Look today how many brands there are.
Look at this example - why is Mercedes up to 60%+ cheaper in the US than in Germany - exact same model. Easy reason I think - because nobody in the US would buy their cars at German prices. Pure marketing logic.
Production technology changes too, they are able to squeeze more elements on a die and that lowers production costs. Multilevel chips can be made faster and easier. I'd be more concerned about spinner HDDs and their prices. It's obvious that mechanical parts prices can go just to some level, adding more capacity is the only thing that makes them viable. SSDs also contain much less material, specially aluminum, magnets, motors heads etc. and as soon as SSDs or other data containers take off at full speed, mechanical drives are bound to go to retirement. Technically speaking, there's nothing that makes mechanical drives better than solid state.