Here are the shop codes for your Tamagotchi V4. The number of gotchi points is what it costs to buy the item.
According to the V4 instruction sheet: At the shop counter screen, press (A). Then, press (A) quickly three times. When the shop owner's face appears surprised, punch in the secret code to reveal a new item.
[A = left button, B = middle button, C = right button]
- Pen = 15,000 gp: BBCA CCCA.
- Steak = 1,400 gp: ACAB ACAC.
- Clone = 14,000 gp: BAAB ACBA.
- Honey = 7,000 gp: CCBA AABB.
- CD3 = 0 gp: CAAA BACB.
The last code you enter does not give you what the code is for; rather, it will give you a cellphone. To get the free CD, simply re-enter the code (it's free anyway!).
We've tested these and they have worked.