All 'round 10
Awesome game, definitely something to play to kill lots of time, though.
Here's a good strategy for it: first buy the S&W magnum when you can, then save for the CZ pistol. Does the same damage as the magnum, but faster reload/firing rate and bigger clip. If neccessary, buy the 350exp machine gun, but afterwards definitely save up for the CZ. After buying the CZ, just kill zombies and repair the base(also get the base up to @225-250 HP) until you can buy the Five-Seven. You can even get the Overkill upgrade to help you. After that, save for the Desert Eagle. The Five-seven is a good enough gun as it is, but the DEagle can do up to 110 damage with the damage upgrade, and along with the overkill and hollow points upgrades, you'll be rackin' in the exp in no time. The speed loader will also help, as it knocks the DEagle down to a .8 reload time. Once you have the DEagle and most of the upgrades, you should be able to make enough for the Pancor in no time. Once you get it, the game is easy killings.