Most people starting retail arbitrage focus on finding "deals." That's the wrong first skill.

The actual skill is margin math — and almost nobody teaches it right.

Here's the framework I use before buying anything to flip:

The 3-fee tax you're ignoring

Every resale platform takes a cut before you see a dollar:

• eBay: ~13% final value fee + payment processing

• StockX: 8-12% depending on seller level, plus shipping

• Facebook Marketplace: 0% (this is why it's the best place to start — no fee tax)

If you're pricing a flip based on retail price minus what you paid, you're already down 10-15% before you even ship it.

The rule that actually protects your capital:

Never buy inventory where your target resale price is less than 2x your all-in cost (item + tax + shipping) for anything under $20. For anything over $50, you need at least 50% margin after platform fees — not before.

Why most beginners "flip" for months and stay broke:

They chase volume instead of margin. Ten items at $3 profit each is $30. Two items at $40 profit each is $80 — with a fifth of the listing/shipping work. Margin discipline beats hustle every time in this game.

Where I actually source (no secrets, just consistency):

Clearance endcaps 2 days after markdown, FB Marketplace "moving sale" posts, and open-box returns — in that order of reliability. The apps and "secret websites" people sell courses on are mostly the same public info, repackaged.

If you're starting from zero: pick ONE category, run the math above before every buy, and sell local first (Marketplace/OfferUp) before you touch shipping and platform fees. You'll keep more of what you make.