I thought a thread like this would be helpful in sharing information about cheap ways to reinforce a room whether that be your hotel room, home or office. I will start with the methods that I know of and then you can feel free to add your own. Please, only list reasonable methods which are economical and expedient.
Master Lock Security Bar $15.50 - Simple bar which mounts behind door knob and has a rubber stop on the bottom which helps prevent forceful entry
Buddy Bar Door Jammer- Essentially a premium version of the Master Lock Bar and claims to work on carpet $75
GE Smart Home Wireless Kit- Has 3 window sensors, 1 door sensor, 120 decibel alarm as loud as car horn $24.00
GE Smart Home door stop- When door is opened, 120 decibel alarm goes off.$9.75
Techko hanging door knob alarm - Hangs on knob, once door is open then alarm goes off. $26.70
GE Motion Sensor - $20
Simple motion sensing flood lights and other motion sensors for all occasions - lots to choose from $10