Several thoughts here:
• Color of your wedding gown? Seller says his are "medium cream" colored. If your gown is cream colored these may go better than if gown is white.
My gown is creme.
• Why top grade freshwaters? They are solid nacre and will last a lifetime, while akoyas have a very thin covering of nacre over a bead and will wear out if worn much.
Even the very best akoyas only have about 1/2 mm (+/- a bit) of nacre. Have you looked at what that looks like on a ruler? That is pretty thin! I will say that the older akoya strands (decades ago) have thicker nacre in general than modern ones do, because the oysters used to be left in the water longer. For various reasons they are harvested earlier nowadays.
Now, if you only plan to wear your pearls occasionally, akoyas should last nicely, but if you plan to wear them often, freshwaters are the better choice in my opinion.
I probably will wear them occasionally.
Here is a photo of my Freshadama strand (7-8mm)-- you will see they have very nice luster:
https://www.pearl-guide.com/forum/attachment.php?attachmentid=10435&d=1222185178
Another benefit of buying freshwaters is that they cost less than akoyas. So you can afford to buy some matching earrings, maybe?
Or even a set with necklace, bracelet and earrings, like this one:
http://www.pearlparadise.com/6570-mm-White-Freshadama-Freshwater-Pearl-Set922.aspx
Those are nice but I noticed that they are white. I'm looking for creme.
• I can't assign a grade to the pearls in the auction. Apart from the fact that there are no closeups of the pearls, there is no standard for what A, AA or AAA means; each vendor has his or her own way of grading. I do see at least 2 pearls with obvious flaws.
With those flaws, what do you think a fair price would be for them? Better to buy new than used even if can get used at a good price? (due to no wear)
Akoyas and Freshwaters differ in their luster in that akoyas have a more metallic, harder luster while freshwaters tend to glow more from within. Some people really do prefer the "look" of an akoya strand, and that is simply a matter of taste.