You found something on Facebook Marketplace. The price looks good. The photos look decent. Your finger is hovering over that “Message Seller” button.
But wait. Is this actually a good deal? Or are you about to overpay for something you could find cheaper somewhere else?
We’ve all been there. And honestly, it’s one of the most frustrating parts of shopping on marketplaces. You don’t have time to research every single item, but you also don’t want to get ripped off.
Let’s break down exactly how to figure out if a deal is worth your money.
The Quick Mental Framework
Before we dive into specifics, here’s the simple framework I use for every marketplace find:
- What would I pay for this new?
- What’s the realistic condition?
- What’s my time worth to find it elsewhere?
If the marketplace price is less than 50% of retail for something in good condition, you’re probably looking at a solid deal. Less than 30%? That’s when things get interesting.
Red Flags That Scream “Bad Deal”
The Price Is Too Close to Retail
If someone is selling a used item for 80-90% of retail price, run. Seriously. You can probably find sales, coupons, or cashback that gets you a brand new one for the same price or less.
The whole point of buying used is saving money. If you’re not saving at least 30-40%, you’re taking on risk (no warranty, unknown history) without the reward.
Stock Photos Instead of Real Ones
When a seller uses the manufacturer’s product photos instead of taking their own, that’s a yellow flag. Best case, they’re lazy. Worst case, they’re hiding something.
Always ask for real photos. If they won’t provide them, move on. There are plenty of other sellers.
Vague Descriptions
“Works great!” tells you nothing. Good sellers explain:
- How long they’ve owned it
- Why they’re selling
- Any flaws or issues
- Whether they have the original box, accessories, manual
If the listing is two words and a price, the seller either doesn’t care or doesn’t want you asking questions.
The “Firm on Price” Attitude
Look, I get it. Some sellers know exactly what their item is worth and don’t want to haggle. That’s fine.
But if someone is defensive about their pricing before you even ask a question? That’s usually a sign they know they’re overpriced and they’re hoping someone doesn’t do their research.
How to Actually Research a Deal (The Fast Way)
You don’t need to spend 30 minutes researching every item. Here’s my quick process:
Step 1: Google the Product + “Price”
Takes 10 seconds. Just search “[product name] price” and see what comes up. This gives you the current retail baseline.
Step 2: Check eBay Sold Listings
This is the secret weapon most people don’t use. Go to eBay, search for the item, then filter by “Sold Items.” This shows you what people actually paid, not what sellers are asking.
If the marketplace price is higher than recent eBay solds, you’re overpaying.
Step 3: Factor in Condition and Completeness
A PS5 with one controller and no box is worth less than one with the original packaging and two controllers. This seems obvious, but people forget to account for it.
Missing accessories can cost you $20-50+ to replace. Factor that into your calculation.
Step 4: Consider Your Time
This is the one most people skip. If you spend 3 hours hunting for the absolute best deal to save $15, was it worth it?
Sometimes paying a little more for convenience makes sense. But you should at least make that choice consciously.
The Deal Score Concept
Here at Underpriced, we think about deals in terms of a “Deal Score” from 0-100. Here’s roughly how it breaks down:
- 90-100 (Hot Deal): You should probably buy this immediately. It’s significantly underpriced.
- 70-89 (Good Deal): Solid discount, worth buying if you need the item.
- 50-69 (Fair): You’re saving money, but nothing special. Might be worth waiting for better.
- Below 50 (Skip): You’re not getting much value. Keep looking.
The score factors in the item’s retail price, current condition, market demand, and comparable sales. It’s basically doing all that research automatically so you don’t have to.
Real Example: iPhone 13
Let’s say you see an iPhone 13 128GB listed for $450 on Facebook Marketplace.
Research check:
- New price: Around $599-699 depending on carrier deals
- eBay solds: $350-400 for good condition
- Condition: “Good” with some scratches
Verdict: This is actually overpriced. You’re better off buying from eBay where you have buyer protection, or waiting for a better local deal. The seller is asking above market value.
This is exactly the kind of analysis that takes 5-10 minutes manually but can be done in seconds with the right tools.
The Two Questions That Matter Most
At the end of the day, it comes down to two questions:
1. Would you be happy telling a friend about this deal?
If you bought it and your friend asked how much you paid, would you feel good about the answer? Or would you feel like you needed to justify it?
2. Could you resell it for what you paid?
This is the ultimate test. If you couldn’t sell the item for at least what you’re paying, you’re probably overpaying. Good deals have built-in equity.
Stop Guessing, Start Knowing
The truth is, most people overpay on marketplaces simply because they don’t have time to research properly. Sellers know this and price accordingly.
That’s exactly why we built Underpriced. Take a screenshot, get an instant analysis with a deal score, comparable prices, and a clear recommendation. No more guessing, no more overpaying.
Your wallet will thank you.