I live in a condo in Jomtien. With mosquito season upon us I am considering having a screen door installed outside my regular front door. The regular front door opens inward and the screen door would open outward. I'd like the screen door to have some metal bars across it, and a lock, so that it's secure, but otherwise nothing fancy. Does anyone know of reliable contractors in the Jomtien or Pattaya area who could install such a door, and roughly what it would cost?

Thanks in advance for your replies.

What you described is standard in millions of Thai apartment blocks. You can almost certainly find pre-made ones or any welder can make a custom sized one.
 

They have sliders so you can access the regular door handle and a padlock fitting they are security doors with mosquito netting.

 

Note you need to look at the inexpensive apartments to find them.