Speaker companies with a focus on parts quality and measurements

Thiel must be added to the list.  For the "CS" series and older, parts and crossovers are still available from the KY facility.  Happy Listening!

Unfortunately for your budget you are not going to able to find any speaker with speciality in house engineered transducers except a great pair of headphones. Sorry to disappoint you but your budget is firmly in mass market speakers with outsourced parts - perhaps if you look vintage used then you may find something.

That said mass produced speakers with parts from Seas/Peerless and others increasingly all from China can be quite good - so don't feel bad. 

Watkins Generation 4 bookshelf size speaker; right in your price range and the best $ for value you can get.....quality materials, not mass produced, decades of engineering experience behind them. www.watkinsstereo.com 

It would be most helpful if you could tell us what speaker characteristics are most important to you and/or what you'd like to improve upon along with your other equipment and room size.

If you like the Maggie sound, then the Vandersteen line should be to your liking. You can definitely score a pair of used VSM's or Bookshelf speakers for your price range, though I would pair them with a decent (Vandy, HSU, REL, JL) sub for optimum reproduction. 
The Zu are a bit more 'direct', so they may not be your 'cuppa'. The nice thing is you can try them for a month and send them back if you don't like them.
Can you tell us what you are using for amp/pre/source? It would help in narrowing down what will work for you.
B