Earlier quoted context omitted.
Hundreds of dollars for legroom? Are you... sure? For what kind of flights?
I'm most familiar with United. Economy Plus (which is mostly about a bit more legroom) does have a modest premium absent sufficient status that gets you it for free. But Premium Economy that gives you somewhat wider seats as well as legroom gets into the hundreds of dollars. International business has lots of benefits including legroom and lie flat seating but that usually gets into the thousands.
The problem with PE is that it's often not that great of a deal. Unless it's a super busy route, you can usually keep shopping for an upgrade and just go all the way to lay flat business. Side note, when going business class, understand that not all plane layouts and seats are the same. Check seat guru.
Source - I fly back and forth to the EU quite a bit.