In Scrap there is a Junk Shop that contains an exploit enabling you to gain infinite items and infinite money for as long as you choose to repeat the pattern. This is a great way to rack up a lot of money and to collect some very good equipment for much of your party members.

1. Enter the Junk Shop and choose Buy
2. Go up the ladder and pick three pieces of junk
3. Return to the counter and choose Sell
4. Scroll down to Hyperion Bazookas and press your OK button twice (it doesn't matter if you don't have any Hyperion Bazookas)
5. Go back up the ladder and you will be able choose seven items!
6. You may repeat this to your heart's content

• The cost will vary with different characters and how many times you have left and re-entered the shop
  
• Leaving the Junk Shop will result in you needing to Buy again to initiate this from the beginning

Body Armor

• Cyber Suit
  
• Warlord Armor

Head Armor

• Mirror Glass

Foot Armor

• Jet Boots

Shields

• Excel Shield

Gloves

• Cyber Gloves

Swords

• Osc Sword
  
• Twin Sword

Guns

• Thunderbolt
  
• Lethal Gun

I am not the person that discovered this trick. I have simply reworded information from very old guides on GameFAQs from the late 1990s from numerous sources, in order to help simplify how to execute this trick.