Architecture
Role-based guidance for marketplace participation. Load relevant file based on user's role.
marketplace/
├── buyer.md # Price comparison, scam detection, negotiation
├── seller.md # Listing creation, pricing, platform rules
├── builder.md # Marketplace creation, economics, liquidity
├── arbitrage.md # Price gaps, ROI calculations, ToS risks
└── compliance.md # Tax obligations, legal pitfalls, bans
Quick Reference
| Role |
File |
When to Load |
| Buying items |
buyer.md |
Comparing prices, spotting scams, negotiating |
| Selling items |
seller.md |
Creating listings, pricing, handling buyers |
| Building marketplace |
builder.md |
Designing platform, economics, payments |
| Arbitrage/Reselling |
arbitrage.md |
Finding price gaps, calculating true ROI |
| Legal/Tax questions |
compliance.md |
Tax nexus, ToS violations, suspensions |
Core Rules
1. Platform-Specific, Never Generic
- Each platform has unique fees, rules, and dynamics
- eBay auction ≠ Amazon Buy Box ≠ FB Marketplace negotiation
- ALWAYS specify which platform advice applies to
2. Total Cost, Not Sticker Price
- Include: platform fees, shipping, taxes, return costs
- Amazon referral fee varies 8-45% by category
- eBay 13%+ Poshmark 20%+ Mercari varies
3. Scam Pattern Recognition
- Stock photos on local marketplaces = red flag
- "Ship to my address, I'll pay extra" = triangulation fraud
- Payment outside platform = no protection
- New account + high-value item + urgency = likely scam
4. Pricing Research = SOLD, Not Listed
- Listed prices mean nothing—items don't sell at listed price
- Always research completed/sold listings
- Factor in condition: "Good" vs "Very Good" = 30% price difference
5. Suspension Risks Are Real
- Amazon ODR >1% = account death
- Review manipulation = permanent ban
- IP complaints from brands = immediate suspension
- Multiple accounts = instant termination
6. Fee Complexity
Never estimate fees—calculate exactly:
- Amazon: referral + FBA + storage + return processing + advertising
- eBay: final value (category-specific) + promoted listings + payment
- Factor returns into margin (15-30% in some categories)
7. Real-Time Data Required
- Never quote prices from memory/training data
- Inventory and pricing change hourly
- Competitor stock levels affect optimal pricing
- Always verify current marketplace state before advising
1---2name: marketplace3description: Navigate online marketplaces as buyer, seller, or builder with platform comparison, listing optimization, and scam detection.4---5
6## Architecture
7
8Role-based guidance for marketplace participation. Load relevant file based on user's role.
9
10```
11marketplace/
12├── buyer.md # Price comparison, scam detection, negotiation
13├── seller.md # Listing creation, pricing, platform rules
14├── builder.md # Marketplace creation, economics, liquidity
15├── arbitrage.md # Price gaps, ROI calculations, ToS risks
16└── compliance.md # Tax obligations, legal pitfalls, bans
17```
18
19## Quick Reference
20
21| Role | File | When to Load |
22|------|------|--------------|
23| Buying items | `buyer.md` | Comparing prices, spotting scams, negotiating |
24| Selling items | `seller.md` | Creating listings, pricing, handling buyers |
25| Building marketplace | `builder.md` | Designing platform, economics, payments |
26| Arbitrage/Reselling | `arbitrage.md` | Finding price gaps, calculating true ROI |
27| Legal/Tax questions | `compliance.md` | Tax nexus, ToS violations, suspensions |
28
29## Core Rules
30
31### 1. Platform-Specific, Never Generic
32- Each platform has unique fees, rules, and dynamics
33- eBay auction ≠ Amazon Buy Box ≠ FB Marketplace negotiation
34- ALWAYS specify which platform advice applies to
35
36### 2. Total Cost, Not Sticker Price
37- Include: platform fees, shipping, taxes, return costs
38- Amazon referral fee varies 8-45% by category
39- eBay 13%+ Poshmark 20%+ Mercari varies
40
41### 3. Scam Pattern Recognition
42- Stock photos on local marketplaces = red flag
43- "Ship to my address, I'll pay extra" = triangulation fraud
44- Payment outside platform = no protection
45- New account + high-value item + urgency = likely scam
46
47### 4. Pricing Research = SOLD, Not Listed
48- Listed prices mean nothing—items don't sell at listed price
49- Always research completed/sold listings
50- Factor in condition: "Good" vs "Very Good" = 30% price difference
51
52### 5. Suspension Risks Are Real
53- Amazon ODR >1% = account death
54- Review manipulation = permanent ban
55- IP complaints from brands = immediate suspension
56- Multiple accounts = instant termination
57
58### 6. Fee Complexity
59Never estimate fees—calculate exactly:
60- Amazon: referral + FBA + storage + return processing + advertising
61- eBay: final value (category-specific) + promoted listings + payment
62- Factor returns into margin (15-30% in some categories)
63
64### 7. Real-Time Data Required
65- Never quote prices from memory/training data
66- Inventory and pricing change hourly
67- Competitor stock levels affect optimal pricing
68- Always verify current marketplace state before advising
johnalbertini14-glitch