To buy Christmas items there's a couple of ways. Firstly it's suggested to travel to Vega. But be warned, you will need either
Christmas Present bags 
or Christmas Tokens 
To travel to Vega it can be accessed by taking the Nordic Ferry North west in Carlin which will cost around 20 gp. You just ask the NPC to travel you to Vega. Next, you need to go to NPC Ruprecht whom is North west in Vega next to Santas hut
This is our pal Ruprecht. Once you meet with him you can trade in Christmas Present Bags for Christmas Tokens. To obtain Christmas Tokens you can participate in the event called Lightbearer which happens once a year in November and light one basin and you get rewarded 50 Christmas Tokens. However, if you want more coins you will have to exchange Christmas Present Bags for the Tokens. To obtain the Christmas bags you will have to participate in the Santa Event.
There's a creature called Grynch Clan Goblins whom drop this bag. It has two phases, the first phase starts on December 12 when Santa Claus and Messenger of Santa are spotted in every city, the second phase starts on December 20 when Grynch Clan Goblins invade every city every day. The event ends on December 31. Through this event you are able to get a number of Christmas-related items. Usually, at least one new Christmas-related item is implemented at every Winter Update. If you want to know a list of all the items you can get please click here- What items can I obtain by trading my Christmas Tokens?
This brings me to my next discussion, you can also get cool items from Grynch Clan Goblins that are Christmas related. Like Candy canes, snowballs, gingerbreadman, and my favorite-A Snowman Package!!
*Little holiday hint you can also get snowballs and gingerbreadman by making them yourself!
Another way to get items would be to visit Santa and ask for a Present. You can get presents from him that are Christmas related. To find him: he can be found in or near each major town, usually near the Depot during Christmas time (Source)
Ab'Dendriel: Underground shops, near Shanar.
Ankrahmun: In the Tavern west from boat.
Carlin: At Dane's shop (underground), south west of depot.
Darashia: South of town, next to the Tavern.
Edron: Inside Castle, next to the Depot.
Farmine: In the Tavern west from the steamship.
Gray Beach: Inside the Depot.
Kazordoon: Jolly Axeman Tavern.
Liberty Bay: West of the depot.
Port Hope: Grassy area south of depot.
Rathleton: In the Grand Opera Café, west from depot.
Svargrond: West of depot.
Thais: At Frodo's shop, north east of depot.
Venore: Under main depot.
Yalahar: In the Tavern east from depot.
Santa also has a helper near him in every city that sells goods please see below!
This NPC sells Christmas items for cheap. My favorite is the Christmas Tree but this will disappear sadly when Christmas is over!!! If you want a Christmas Tree forever this brings me to the last way to celebrate Christmas forever....
Tibia coins can be purchased with real life money or by buying it in the Market. All you need to do is access your store and Christmas is but one click away. You can get mounts or festive items! Please see below for examples and have a Merry Christmas!
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