Yes, I'm pretty sure every lanyard is €10.
Most booster sets are €18.99 but i did see one in the ToT shop that was four pretty small Winnie the Pooh pins for €16.99. Almost all the booster sets are 4 pins; tbh I've never seen a 6-pin set there but by all means buy one if you can find it!
As for pins themselves the cheapest I've seen is €7 but then they go up the bigger and more fancy you get, e.g. dangly bits, sparkles/rhinestones, multiple layers, etc. The most expensive singles are €14.99 I believe but those are really only limited edition for that much money.
In our family my daughter and I do pin trading; we started it on our cruise and we love it! Have fun!
Sariah x