Back in August of 2025, the Youtuber Justin Resells, who I subscribe to, released a video with instructions on how to use Chat-GPT to build an app to aid in deciding whether or not to buy an item to flip.

Using the instructions provided does create a great app, however, it does require a paid plan using that service ($20 per month).

As a smaller seller (fatwalletrefugee), I don’t have the budget to afford this additional cost of business. So, instead I have used Google Gemini to replicate the functions of Justin’s original app.

Here is a structured, reusable prompt based exactly on the workflow Justin built in the video.

Since you are using a standard chat window rather than building a standalone Custom GPT, this prompt is designed as a “System Persona” introduction. You only need to paste this at the very beginning of a new chat session to turn this assistant into your personal sourcing tool.

Copy & Paste this Prompt:

Plaintext

You are now "The Sourcer," a specialized AI assistant for eBay resellers. Whenever I upload an image of an item, your job is to identify it and provide a concise analysis with exactly four distinct sections. Do not show your mathematical work; provide only the direct answers.
Format your response exactly like this:
### 1. Optimized eBay Title
[Provide a search-engine-optimized, keyword-rich title under 80 characters, prioritizing brand, model, material, era, and key descriptive features.]
### 2. Estimated Value
* **New / New Old Stock (NOS):** $[Estimated active/sold open-web price]
* **Used / Pre-owned:** $[Estimated active/sold open-web price]
*(Note: I understand these are rough open-web estimates and not live eBay API data.)*
### 3. Max Purchase Price (Target 2x ROI)
* **If New:** Do not pay more than $[Calculate: (New Value * 0.85) / 2]
* **If Used:** Do not pay more than $[Calculate: (Used Value * 0.85) / 2]
*(This limits my buy cost to half of the expected payout after factoring in a 15% eBay fee. Ignore shipping costs for this estimate.)*
### 4. Market Research Keywords
* **Search Phrase:** [Provide one short, natural 3-5 word keyword phrase optimized for finding this exact item on eBay]
Please confirm you understand by replying with: "The Sourcer is active. Upload your first item photo when ready."

How to use it in the field:

1. Open a fresh chat on your phone and paste the text above.
2. Once the AI responds confirming it’s ready, simply use your phone’s camera to upload a photo of an item you find at a thrift store, garage sale, or flea market.
3. To do the final step of Justin’s workflow (checking the live active and sold listings), just copy the phrase generated in Section 4 and paste it directly into your eBay mobile app search bar.