These are the weapons as of Stick RPG 2 v1.2.
Pistol: From Steel & Hawk for $685.
Glock: From Arms Dealer Larry for $9050.
Doomsday Glock: Win by getting 3 ammo in a row at slot machines, Premium Weapons Dealer at Benjamin's Club, or the Contraband Salesman near Skye's bar for $1,337,000.
Old Baseball Bat: From Steel & Hawk for $235.
Major League Bat: From Arms Dealer Larry for $5,500.
Hall of Fame bat: From Max out Drug Dealer profession.
Ornamental Katana: From Steel & Hawk for $490.
Carbon Steel Katana: From Arms Dealer Larry for $6200.
Masamune: Max out the Video Game Designer profession.
Machine Gun: From Arms Dealer Larry for $13,850.
AK-47: Clear the Mobster Tower.
Single Barreled Shotgun: From Arms Dealer Larry for $3,800.
Double Barreled Shotgun: Clear Gangster's HQ.
Combat Shotgun: Max out Police Officer profession.
Weathered Sledge Hammer: Give toilet paper to the man in Skye's bar restroom.
Heavy Sledge Hammer: Give Einsteinium and Sledge Hammer to the guy in the laundromat.
Super Sledge Hammer: Give Unobtainium and Better Sledge Hammer to the same guy at the laundromat.
Mini-Gun: From Arms Dealer Larry at The Dangling Pianist for $20,900.
Chain-Gun: From Premium Weapons Dealer at Benjamin's Club for $87,000.
Glowy Sword: From Arms Dealer Larry at The Dangling Pianist for $3,100.
Prototype Railgun: From Arms Dealer Larry at The Dangling Pianist for $27,600.
Blast Cannon: Defeat Defeat Tutorial Ted about the case of inspecting Ryan's death.
The Auto-Railer 9000: Premium Weapons Dealer at Benjamin's Club for $4,900,000.
Home Brew Flamethrower: Give Leaf Blower, lighter and 40 oz. to Pyro Perry.
Modified Flamethrower: Give fuel cell, Screwdriver, Cheap Watch, and your Homebrew Flamethrower to Pyro Perry.
Nova Flamethrower: Give Solar Matter, 4D hypercube, and Modified Flamethrower to Pyro Perry.
The Zappy Hat: Defeat the guy near the Dangling Pianist.
Secret Weapon: Get by maxing out Hit-man profession.
70cc Chainsaw : Max out Lumberjack profession
55cc Chainsaw : From the Hardware store for $4,700.
45cc Chainsaw : From the Hardware store for $650.
Electro Helmet : From Arms Dealer Larry at The Dangling Pianist, $18,550.
Dark Laser Sword: Max out Dark Lord profession.
Light Laser Sword: Max out Light Knight profession.
The King: Max-out Government Official Profession.
Tesla Helmet : Max-out maxing out teaching profession.