This is a LOW PROFILE card so should fit, and can work with most 300W supplies. It will however cost more than your budget since it's $160 but I simply can't recommend anything else with your PSU and wish to run Dayz.
If you can't stretch your budget I suggest finding a slim HD7750 though they may cost at least $100. The GTX750Ti uses the new Maxwell GPU so it's very power efficient. It's the most POWERFUL graphics card a 300W Power Supply can run.