Real-profit thinking
Every worksheet accounts for the parts that disappear in a quick sale: platform fees, shipping, promos, supplies, and your purchase cost.
MTC Seller Lab by MTC Collectibles
Turn Inventory Into Income.
Everything you need to organize, price, sell, and grow your collectibles business.
Built by a reseller. Powered by AI.
Buy smarter. Sell faster. Know your real profit.
SellerStack snapshot
Know the numbers before you list.
Net profit
$128.40
Return on investment
42.8%
Platform fees$26.10
Shipping + supplies$14.50
Recommended list price$249.00
Real reseller proof
Trusted by real collectors and resellers.
- 1,500+ Whatnot Sales
- Thousands of collectibles sold
- Experience across eBay, Facebook Marketplace & Consignment
- Built from real-world selling—not theory
Built for the work behind every sale
Turn proven reseller experience into a better operating system.
Clear, collectible-specific systems
Condition notes, manifests, grading trackers, show notes, and buyer messages made for the inventory you actually handle.
Practical support as you grow
Use the tools at your pace, then join office hours and community conversations when you want a second set of eyes.
The SellerStack workflow
From a pile of inventory to a repeatable resale routine.
Start with a clean profit decision. Then build listings and records that make your next sale easier—not more complicated.
Start with the free calculator01
Price with the whole sale in view
Run the numbers before you commit.
The free Collectibles Profit Calculator helps you check purchase cost, platform fees, shipping, promotions, net profit, and ROI before an item goes live.
02
List without staring at a blank screen
Turn condition, photos, and comps into clear listings.
Use title formulas, Whatnot show notes, Marketplace descriptions, photo checklists, condition language, and buyer-message templates tailored to collectible selling.
03
Keep the back office calm
Know what you own, sold, shipped, and need to follow up on.
SellerStack Pro brings inventory tracking, consignment manifests, grading submissions, dispute responses, stream planning, and a monthly sales dashboard into one working kit.
Choose your next move
Useful tools now. Ongoing support when you want it.
Buy one focused resource, get a hands-on audit, or join the Club for fresh systems each month.
Start with one smarter decision
Find out what your next collectible sale is really worth.
Download the free calculator, build a clearer baseline, and make your inventory work harder without turning your collection into a full-time retail operation.