Instead, very early in the fight one of them dropped a Harpoon. I had no idea what it was but when i tried it out it turned out to be an awesome weapon, which made fighting off the rest of the goblins much easier. Then when i checked my inventory again afterward i found that A: I'd grabbed enough loot to get me over the 50 gold mark, what i needed for the machine gun when the Armorer finally showed up, and B: I had a pair of Rocket Boots! Rocket boots are dropped by goblins but are exceptionally rare. They basically let you fly for short distances and everyone who doesn't have one wants one.
With the Rocket Boots and the Harpoon i was able to go start smashing Shadow Orbs easily. The very first Orb i smashed dropped a Musket, which was the even needed to get the Armorer to show up so i could get the machine gun. Then there was a little problem with a new bug/"feature", but i eventually managed to fight the second boss, the Eater of Worlds. I died, due to some stupid stuff on my part, but picked up a lot of awesome loot before i did. I then fought the first boss a couple times, handling him easy using the machine gun, and then went back to Eater of Worlds and the second time i took him out with fairly little problem. That gave me enough materials to build Shadowscale Armor, one of the second from the top tier armor sets, along with a lot of "Nightmare" tools and weapons.
So one very lucky Goblin Invasion and another couple hours of work and the capabilities of my character have massively increased, yay! :)