Local-first secondhand offer calculator

Know the mathbefore youmake the offer.

Turn the seller ask, expected value, real costs, and your margin into a fair offer, a confident opener, and a hard walk-away number.

Open App Store Open Google Play Try the worksheet

Status: Live on iOS and Android
Data: Local-first, no account
Decision: Buy, counter, lowball, or pass

A rugged offer-planning workbench with calculator, comparable-sale notes, target dial, and offer card. — Transparent inputs. Visible math. Your call.

The product rule

Fast math. Human decision.

You control the numbers

You enter the ask, value, fees, shipping, and risk. The app does not invent a market price.

The math stays visible

Every result maps back to the values you supplied—no mystery multipliers.

No hidden pricing feed

No automated marketplace scraping, no required login, and no surprise feed behind the answer.

Offer worksheet

Your numbers. Your plan.

Stress-test a seller ask against expected value, unavoidable costs, risk, and the margin you actually need.

Suggested call COUNTER

Offer below ask and keep the walk-away tight.

Fair offer$0

Lowball opener$0

Walk-away$0

Profit at ask$0

ROI at ask0%

Total friction$0

Illustrative planning math only. Verify value, condition, authenticity, fees, and safety before buying.

How it works

Three moves before the message.

Build the target, check the gap, then negotiate from a number you understand.

Set the target

Bring the seller ask and the item value you can defend. Add the condition and pickup reality.

Worth to me: $246
Walk-away: $267

Check the gap

See how the ask compares with your fair number after fees, repairs, shipping, and risk.

Ask: $295
Gap to fair: $49

Make the offer

Open with confidence, keep your range in mind, and be ready to leave at the ceiling.

Opening offer: $177
Plan: Counter

Built for the moment

Use it before you reach out.

Browsing

Quick listing check

Know the range before you start a message thread.

Pickup

Run the spot check

Update condition and costs while the item is in front of you.

Counter

Respond with a plan

Keep the walk-away visible when the seller comes back.

Feature ledger

Tools that keep you in control.

Free covers the core offer decision. Pro adds deeper repeat-use tools without changing the local-first model.

Offer math

Fair offer, aggressive opener, walk-away, profit, ROI, and verdict.

Free

Guided checks

Risk prompts and category-specific checks before you commit.

Free + Pro depth

Research shortcuts

User-initiated comp and retail searches from the item title.

Pro

Journal and saved deals

Keep notes, offer ranges, deal records, and Pickup Proof locally.

Pro

Local-first privacy

No app account, no Newman cloud for deal data, and no analytics SDK.

Always

Lowball Lab Pro

Pick the path that fits your deal volume.

The app installs free. Optional Pro purchases are handled by Apple or Google, with localized store pricing shown before purchase.

7-day trial

Monthly

$2.99 per month

Flexible access for active deal runs.

7-day trial

Annual

$24.99 per year

The lower-cost subscription path for regular buyers.

No trial

Lifetime

$49.99 one time

One purchase for the lifetime Pro entitlement.

Monthly and Annual include a seven-day trial where offered. Lifetime is a one-time purchase and does not include a trial.

View on App Store View on Google Play

No guesswork hiding in a black box.

You enter. You see. You decide.

No automated pricing feed
No hidden multipliers
No guaranteed profit
No marketplace login

Fast answers

The deal math in plain terms.

Use caseWhat is Lowball Lab for?

Lowball Lab helps secondhand buyers check a seller ask against resale value, costs, risk, target margin, profit, ROI, and a buy, pass, counter, or lowball verdict before messaging.

StatusIs Lowball Lab live?

Lowball Lab is live on the App Store for iOS and on Google Play for Android.

PrivacyDoes Lowball Lab scrape marketplaces or require a login?

No. Lowball Lab is built around local calculation and user-confirmed comp checks. It does not promise marketplace scraping or require a marketplace login.

OutputWhat numbers does the calculator show?

The calculator shows a fair offer, lowball opener, walk-away ceiling, profit at ask, ROI at ask, total friction, and a simple verdict for the deal.

Field notes

Keep the decision useful.

Offer-math checklistRun the full cost and margin check. Comp-check workflowConfirm a value without pretending it is automatic. Lowball updatesPublic release notes and product changes.

Make the next offer with a plan

Get Lowball Lab update notes.

Join for focused release notes and product feedback asks. This list is only for Lowball Lab.

Read release notes