How Much Is a Sig M18 Worth? (2026 Value Update)

What Affects the Value of a SIG Sauer M18?

SIG M18 value is affected by the gun’s condition, variant, and accessories or upgrades.

Condition and Value

Used SIG M18 prices are better when the pistol itself is in better condition.

For accurate valuation, you can go to local FFLs to get your gun graded by a professional, though some of them charge fees.

To see how we professionally evaluate your firearm (for free) and turn that condition into a payout, view our 3-step selling process for a guaranteed FFL offer.

Here at Cash for Arms, we give free gun appraisals for any gun you’re looking to sell. Once you learn the grade of your gun, you can use this as a guide for price.

Like-New or Mint

• Closest to retail price
• Unused
• No visible marks
• Perfect function

Excellent

• About 10% less than mint
• Very light use
• Barely visible marks
• Fully operational

Very Good

• About 20% less than mint
• Light use
• Light marks
• Fully operational

Good

• About 30% less than mint
• Regularly used but maintained
• Some wear marks and possible scratches
• Fully operational

Fair

• About 40% less than mint
• Regularly used and unmaintained
• Heavy wear marks and scratches
• Mostly operational

Poor

• About 50% less than mint
• Regularly used, unmaintained, and possibly broken
• Broken, pitted, dented or heavily rusted
• Not operational and might need repairs

How We Appraise SIG M18 Models

There are several versions of the SIG M18. They’re actually very similar to each other and most of them cost the same. The differences are from them being tailored to comply with some states’ strict gun rules.

SIG P320 M18 Price (Standard Model)

The average used SIG P320 M18 is worth $232 to $428. A new SIG P320 M18 costs $649.99 at retail.

This is the base SIG M18 chambered in 9mm, featuring a 3.9-inch non-threaded barrel, coyote tan finish, and base magazine of 21-round steel mags.

SIG P320 M18-10 Price

The average used SIG P320 M18-10 is worth $232 to $428. A new SIG P320 M18-10 costs $649.99 at retail.

This variant was made to be complaint in the states of Connecticut, Hawaii, Illinois, Massachusetts, Maryland, and New Jersey. It has a threaded barrel and 10-round steel mags.

SIG P320 M18-CA Price

The average used SIG P320 M18-CA is worth $232 to $428. A new SIG P320 M18-CA costs $649.99 at retail.

This variant was made to be compliant with the laws of California. It also comes with a threaded barrel, standard polymer grips, and 10-round steel mags.

SIG P320 M18 Commemorative Price

The average used SIG P320 M18 Commemorative is worth $350 to $660.

Only 5000 of these variants are made. This is similar to the base model but it comes with a special serial number (M18-0001 to M18-5000), a unique challenge coin, certificate of authenticity, and a collector’s case.

This is a model that holds value well. Because it’s a premium firearm in the line, we use a secure gun shipping and buying system to ensure every transaction is fully insured and legally compliant.

How Accessories Affect What We Pay for Your SIG M18

Since SIG M18’s are modular, a lot of sellers typically bundle the gun with multiple modifications to make the gun more valuable.

This is still dependent on the buyer, as some prefer to buy only the base gun. Worn or low quality accessories might also get a haircut on value.

Original Box and Papers

If you have it in great condition, consider offering it as it can help with resale value.

Value: Usually adds $5 to $15, depending on condition.

Optics

High-quality optics from a well-known brand or from SIG themselves can definitely hike up the value.

Value: Around 30% to 50% of the accessory’s original value.

Weapon Laser/Light

Lights or lasers from a well-known brand will surely help with the value though less preferable than optics.

Value: Around 30% to 50% of the accessory’s original value.

Spare Magazines

It’s never bad to have more mags, especially if you have more SIG 21+1 mags.

Value: Around $10 to $15 per used mag.

The Process to Sell a P320 or M18 to Us

Selling a SIG shouldn't be complicated. Whether you have a P320 or M18, we provide a streamlined process that handles the heavy lifting for you.

• Step 1: Get an instant quote based on your gun’s specific model and condition.
• Step 2: Accept our offer and ship your gun with our prepaid label.
• Step 3: Get paid the same day we validate it.