Yup, played and beat the game
autospike posted. Here is my strategy in the order I got them in.
1. Use the least amount of firepower per enemy.
2. Upgrade to the .22 ASAP.
2a. Use the ammo from the weaker gun first unless enemy requires a shot from the stronger gun. AKA, BB gun then 22, 9mm pistol then shotgun, 9mm carbine then shotgun. This does not apply when you have frag gernades, use those when you can take out multiple enemies.
3. Get boards over the windows after you get the 22.
4. Save up until you can get the 9mm or the 45. Don't get both, keep the 22 for the small guys. Fast reload time is you're friend.
5. Get the iorn gate as soon as money allows. This gives you a little standoff room. They need to get through this before they get closer to the house. If you are empty, this will buy you time to reload.
6. Get the shotgun next. Only use it when needed since it has a slow reload time and small mag.
7. Save up and get a few more defences. I got razor wire. Don't spend all you're money on defences without upgrading weapons.
8. Get the 9mm carbine, don't bother with the sniper rifle. It is overkill on the small enemies and the mag size and reload time will kill you. Keep the shotgun as secondary and use when needed.
9. Get frag gernades, don't bother with the Molotovs. Yes they are cool, but gernades are much better. Keep 9mm carbine as primary and use gernades when you can take out multiple zombies.
10. After you have the 9mm carbine and gernades, if you are still alive, load up on defences. They will take the brunt when you are reloading.
That is how I did it.