A winning flip has two phases: getting paid and getting the item to the buyer. Those are different jobs. Square is relevant to in-person card acceptance; ShipStation is relevant to managing shipped orders. Neither makes an unprofitable item profitable.
Affiliate disclosure: ResaleValue.co may receive compensation if you sign up through the partner links on this page. We compare use cases independently, not as guaranteed savings. Full disclosure.
1. Decide how the buyer will pay
Mostly eBay, Etsy or another marketplace? Use the platform's required payment workflow. Don't move a protected marketplace transaction outside the service just to avoid fees.
Local pickup, vintage fair or flea market? Square offers mobile in-person card acceptance. Eligible new US sellers can get a first free magstripe reader. That small plug-in device accepts swiped cards and does not read chip cards; contactless/chip hardware is different. Verify device compatibility, eligibility and transaction fees.
Taking in-person payments?
Compare the available Square options and read the hardware terms. This tracked partner link selects Square's reader offer. The free first reader shown is the magstripe (swipe) model, not Square's separately sold chip/contactless hardware.
See Square’s reader offer ↗Square affiliate link · Square may pay us if a new business activates.
2. Make shipping an actual cost, not an estimate
Before choosing a shipping platform, record the packed weight, dimensions, destination zone, packaging cost and any buyer-paid shipping. Marketplace label discounts and carrier rules vary; you cannot assume the cheapest option without comparing actual packages.
Use the ResaleValue calculator to test that order with the real sales fee and postage expense. If the shipping tool carries a monthly subscription, consider allocating that cost across shipped orders.
Shipping across marketplaces?
ShipStation can bring supported channel orders into one workflow, compare carrier services and produce labels. It is not a checkout or payment gateway. Review plan pricing, integrations and trial eligibility yourself.
Explore ShipStation ↗ShipStation affiliate link · No guaranteed postage savings.
3. Pick the right tool for your situation
| Your business | Likely priority |
|---|---|
| Occasional local pickup | Payment acceptance and recordkeeping; card reader only if customers need it. |
| Occasional one-marketplace shipment | Use built-in shipping until volume justifies another service. |
| High-volume seller on several marketplaces | Explore shipping automation and order synchronization. |
| Pop-up shop with mailed follow-up orders | Evaluate both payment acceptance and fulfillment separately. |
4. Track real net profit
Keep a consistent record of gross receipts, platform fees, payment processing, shipping paid, packing supplies, returns and overhead. A "free" reader doesn't remove transaction fees; a shipping dashboard doesn't guarantee a discount. Use your own numbers.
Need step-by-step selling help? Our sister guide at ThriftFlipping.com covers the real flea market reader use case, with a separate shipping workflow guide.
Reviewed November 2, 2026. Official information: Square reader compatibility and offer · ShipStation integrations.
