Where can you get an affordable functional gambeson?

I’ve discovered what I call two classes of gambesons. One being thinner than the other and is best worn under armour for protection from the armour. The other being thicker and best suited for protection from incoming blows. The former is much more comfortable while the latter is hotter, not that the first is cool. Also, the latter is more tiring due to the weight, heat, and effort just to bend the arms. Although mine has detachable sleeves. Not only that there are two sets of sleeves, one being long and the other half sleeve. I’ve only used the long sleeves. One was made for me by a forgotten vendor on ebay and the other a peg item from KoA.

www.kultofathena.com/?s=gambeson+&post_type=product&dgwt_wcas=1

www.amazon.com/s?k=gambeson&crid=1EWDG7N548UUV&sprefix=gambeson%2Caps%2C165&ref=nb_sb_noss_1

define 'affordable'
Because if you are cheap in this, you'll get junk.

What about around the price range of Museum Replicas' Gambesons or those in the links posted such as Kult of Athena's? If those ones do count as real gambesons?

Although if not then what would be the lowest range for 'real gambesons' available?

You asked about “Real” Gambesons:

Per my understanding, medieval and renassiance European gambesons varied quite a bit based on fashion and intended function. Gambesons were made primarily made of linen canvas and wool. The outermost and innermost layer were linen canvas. I’ve heard of gambesons containing as little as three inner layers of wool blanket. I’ve also heard of gambesons consisting of 15 layers of linen. But generally, they had some combination of linen and wool. Arming jackets worn under plate armor could be very thin, perhaps only an inner and outer layer of linnen canvas.
Whether or not the gambeson was intended to be the primary defense would impact the thickness. If the gambeson was intended as your primary defense, it was typically made thicker. If the gambeson was intended as a layer to be worn under armor, it was typically thinner.
The shape of the gambeson was also cut fashionably, consistent with the time period. So a gambeson appropriate for 1200 is going to look old timey to a knight circa 1350.

All that being said, here is my opinion: I wouldn’t sweat over the thickness (pun intended). For historical re-enactment purposes, no one other than you is going to notice that the gambeson is made from cotton canvas and not linen canvas. You’ll spend more on raw materials acquiring enough linen canvas and wool fabric than you would buying any gambeson from Kult of Athena. Since you intend the gambeson to be the outside layer of your armor, find some artwork from the time period you want to re-enanct. Pick a gambeson that looks consistent with the style you see. That is far more noticeable than thickness and materials. Also, I recommend sticking to all natural materials. Synthetic fill is warmer than cotton batting.

So I tried getting some gambeson chausses from these guys who call themselves "The Medievals" on eBay/Amazon and they didn't seem really good at all. Its way too thin, do their gambesons that they sell also have the same problem? www.amazon.com/dp/B09D9W3QNR

This is their gambeson top btw: www.amazon.com/dp/B08VS132C7