Real or fake product

I also see lots of deals (usually not in shops, but in private sellers) of watches only with cable, without box or warranty.

Where all these come from? 

I think is difficult to make fake Garmin watch - it is quite complex watch and is easy to check if it really works as should. Maybe those products are stolen and therefore without the box. There are also people throwing out boxes too, so it may be also this case. Me personally have all my watch boxes exactly for the case of selling it creates more trust.

I know that people tend to throw boxes and I understand it, but we talk about brand new unused watches with the stickers on top. In some of the listings they mention that the watches come from some sponsorships, but it really looks shady. 

I have just bought one (5x saphier) on Amazon.co.uk, for eur 290; indeed, in a Garmin box, but NOT original package, with all accessories, booklets, according to the notice with Garmin guarantee. It is definitely a new, unused product and also 100% sure genuine. 

According to the seller it would be a 'refurbished' item; my guess is showroom model. Anyway, very happy with it, price is much more fitting, than the shop prices (here in the Netherlands about eur 800).

Enjoy the perfect watch

Seems unusual to not include a retail box but price is to low for these watches but hay ho . on a footnote i notice that Garmin no longer etch the serial numbers on the back of the case ,my Garmin 5 x is 4 months old bought from a retail store in the box and the serial numbers on the box and watch case tally up .I was considering an upgrade to the Fenix 6 but these issues leave me wondering 

On the fenix 6 the s/n isn’t etched on the rear as it was on my 3 and 5. But it is there - on the side under the strap bar...

I just bought a refurbished Fenix 5 yesterday for half the regular retail price, from a reputable dealer in Canada, it came in a generic oversized Garmin box that was printed "Refurbished product" all over it, watch was inside in a bit of bubble wrap with cable and documentation, but otherwise no product-specific box. Maybe the ones you're seeing on the market are refurbs...

what was the price if you want to share it?

I would suggest your ability to trust the product depends on your intended use. If you aren’t going to rely on watch functions like navigation, then maybe you don’t care so much about authenticity. In my case, I use my Fenix as a backup navigator and as such, I want to ensure it is what it says it is.