I've sold perfume sample (lots, not singles) on ebay. They are popular for several types of gals:
1) Those who live far from stores that offer samples
2) Those who travel and can't take a full bottle on a plane
3) Those who want something that's discontinued
A lot of stores around here don't give out samples unless you buy something. The exception is Nordie's which I happen to have one close, thank heaven.
I was seasonal in fragrances at Macy's 2 Christmases ago and have forgotten a lot
JC scents are always there for sale, but unless the JC reps are there, no samples of the JC stuff can be found. There are really only few main companies that sell scent, I was surprised to learn. For example Aramis covers all the Estee Lauder line,
Coach, Donna Karan, yadda yadda. Elizabeth Arden is the parent company for JC.
Anyway...my point being, not everyone has access to free perfume samples.
And yeah, you really gotta watch those eBay descriptions. I've read some hilarious feedback from sellers who don't list properly - they won't be around long if they keep up the deception of showing a photo of a full bottle and sending a sample card!
That link to the seller looks like a clear listing. Given it has shipping included, $5 isn't a big price gouge. Postage is a minimum of $1.65, padded envelopes & labels cost something, ebay & PayPal take about 80 cents in fees...they can't be making more than $2 on it and that's only if they get the samples free and buy padded envelopes & labels/ink in bulk. Kind of a lot of work for $2. Most of that $5 is going towards the shipping & handling.