The first item is listed on Australian Ebay. Was that the only place you could find it? Better to deal on standard Ebay. They are though a US Seller.
I would never attempt to buy anything "live" from overseas sellers. Can get confiscated by Customs and might die in transit. Seeds are not usually a problem, though you may need to get an APHIS Permit in the Small Seeds program. Some seeds need to be ultra fresh for some tropicals, so need to be careful there since the freshest may be from overseas but take foreever to get here
and then get confiscated.
The seller at first glance looks Superb - he has sold 4,437 items and has a 100 % Feedback rating. The 4,437 is found near upper right after their name. This would be a first class Seller, fer sure.
On Ebay you can Save searches and Ebay will email you when items are listed. You can also make a Seller a favorite (Follow them) and quickly check them out to see if they relist similar items. You can also send a Seller a question; for example, will you be listing this item again? I do that frequently.
Second one as you said is way small. And $8 to ship a bare root 4 " plant is a bit steep in my view. The larger first plant shipped much faster for nearly 3 $ less. Some Sellers Jack up their shipping cost to make extra bucks as the commission they pay is based on selling price excluding shipping. (Others offer "free" shipping to entice you, but their prices are higher. :-))
By clicking on the Sellers Ebay name, you can see comments by others. Hers is the comments for the second seller;
looks good. No Neutral or Negatives
Here First seller.
One Neutral by a guy that likely killed 6 coffee plants - he admitted it :-)
Just based on a cursory review, I would not hesitate to order from either of these folks.
Hope this helps. Keep in mind reputation means everything on Ebay and a good seller will go out of their way to keep high ratings.