Hi clawdia,
I don’t know which vendors send out samples off the top of my head but a quick call to each one you are considering would quickly find out.
I would be very cautious though because pushing down or squeezing a small sample with your hand is very different from sleeping on it because ILD is only part of what makes one layer feel softer or firmer than another. In general though 14 ILD Talalay will be about the softest latex you will find with the possible exception of some of the newer continuous pour Dunlop versions which are softer than most of the molded Dunlop. 19 ILD Talalay would probably be a little softer than 16 - 18 ILD Dunlop for most people. I know that SLAB sells samples here but the site says they are out of 2" and 3" versions so I don’t know what the thickness would be. I would personally test out Talalay as a complete topper or as the top layer of a mattress rather than a sample because it will give you a much better sense of what it feels like to sleep on and even blended talalay will give you a reasonable idea of the “feel” of 100% natural Talalay since they are very similar.
I have a box of twelve different 4" x 4" x 4" samples of blended and 100% natural Talalay (from Radium) and while I can tell the difference between them there is no way I would be able to tell what they are like to sleep on from squeezing samples.
Pure Latex Bliss makes a 2" and a 3" blended Talalay topper that is 14 ILD, a Talalay GL fast response gel Talalay topper that is 15ILD, and a 100% natural Talalay topper that is N1 which is in the range of mid - upper teens. There is a retail store finder on their site here that will tell you the closest stores that carry them and a call will tell you which ones they carry.
There is a list for the Greensboro / High Point, NC area in post #2 here and for the Roanoke area in post #5 here but you would need to call them to find out what type of toppers they may carry.
There is a list in post #4 here of topper and component sources and some of them sell 100% natural Talalay but as you mentioned it’s generally more costly than 100% natural Dunlop or blended Talalay.
Phoenix