The price on the listing is rarely the whole price, and the shop you buy from decides more than the few euros between two catalogues. Shipping, payment, packaging and what happens when a seed fails are all part of what you are paying for, and none of them appear next to the price.
What sits on top of the seed price
Shipping. Charged per order rather than per seed, so it weighs most on a small basket. On a single pack the postage can move the price per seed further than any discount on the seeds does, which makes ordering once rather than three times the easiest saving there is.
Payment. Bank transfer, card and sometimes cryptocurrency are the usual options, and they are not always priced the same. Where a shop charges for one method or discounts another, it says so at checkout rather than on the product page.
Tracking and insurance. Usually optional, and worth the money on anything but the smallest order: an untracked parcel that does not arrive is one nobody can trace.
What a listing should tell you before you order
The pack size, the flowering time, the seed type and the breeder are the four things worth having in front of you, and a listing that states all four is easier to plan with than one written entirely in adjectives. Pack size in particular decides the price per seed, which is the only number that compares one catalogue with another.
Storage is the other half of the question. Seed keeps for years when it is kept cool, dark and dry, so buying more than you will sprout this season is reasonable, as long as you are set up to store the rest properly. The guide to storing seeds covers that.
Discretion and delivery
Plain outer packaging is normal in this trade rather than something a shop advertises. What differs is what is inside it. A labelled tube or a breeder pack keeps the name attached to the seed, which matters once a collection runs to several varieties.
Laws differ from country to country and sometimes within one. Whether a package may be sent to you at all is a question about where you live, not about the shop, and it is worth answering before you order rather than after.
What the index can and cannot tell you
This site indexes 2 shops, and that number is the limit of what a price comparison can do here. Only 5 of the 384 strains are carried by more than one of them, which means most listings have exactly one price and there is nothing to compare it against yet. Where a strain does appear twice, the difference is visible immediately and it is usually larger than the difference between two similar strains.
Across the priced offers, a seed runs from €1.92 to €18.05 with the median at €7.85, and the pack size hides most of that, which the guide on what a seed costs works through.
A short checklist before you order
Work out the price per seed rather than the price per pack. Add the shipping to the basket before you compare anything. Check that the pack size, the flowering time and the seed type are all stated. And buy enough in one order that the postage is worth paying, given that seed keeps for years when it is stored properly.