The e prefix is not popular at all.
In fact, I'd say it was never all that popular with normal people, it was just companies trying to sound cool and then spending ungodly amounts of money trying to advertise the names so peopple would remember them.
These days it's just a reminder of the silly excesses of the .com insanity.
If you want to know the value of the e prefix, figure out what the name would be worth without the prefix, and then move the decimal point two places to the left.
If the word after the e starts with a vowel, move the decimal again. If it has a hyphen, move another decimal spot. If there's more than one word (not including the extension) after the e, move yet another decimal point.
This is just an estimate, but I think it's a good guide.