VCS Hobbies: US Distributor of T Gauge and reseller of TGauge.com products in the US.
Lemiso: German importer that stocks Eishindo T Gauge rolling stock, track, and selected accessories. They have created their own line of 3D printed products; buildings, bridges, and tunnels. The buildings are German-style, but several will work well for generic European or US layouts (and I would guess other parts of the world). Bridges and tunnels are universal, but they have a specific tunnel entrance that you will find on a modern ICE 3 rail network. They support International Shipping and payments via PayPal.
NOTE! At the top of their web site menu to the right, you can customize the language and country (I have linked directly to English Language).
CCE Models: The man behind CCE Models is Jesse Svoboda that has years of experience designing for T gauge. You will find very detailed and accurate models and decals. Note that the models are 3D printed and it will require some assembly and painting. Check out his blog as well.
Shapeway T-scale: You will find a lot of T Gauge items you can purchase from Shapeways. If you are not familiar with Shapeways, it is a 3D printing service. You can upload your own 3D designs and have them printed or buy items from designers that have set up their own shops.
CMR Products: The on-line store has an extensive range of North American railroad and vehicle decals including some weathering decals. Go to [Store] and search for “T scale”. Every decal set has a “Scale” dropdown menu where you can choose “T Scale (1:450)”.
TGauge Buy and Sell: A Facebook group where you can buy and sell used, new and custom made T Gauge products.
CustomZscale: Makes and designs precut card stock kits. You can buy directly from the web site or eBay or Etsy. Primary focus is on Z and N scale but “a bunch” of T gauge structures are also available. From the eBay store, you can buy a couple of building packs that combined gives you about 50+ structures. If you use the Etsy store you can buy individual buildings and you specify the scale with a drop down menu. NOTE that not all structures are available for T gauge. Sean B the man behind customZscale has a YouTube channel where you can see more of the buildings.
Lsgb.RailScale: Supplies vinyl printed liveries and 3D printed shells. You can get kits or as “ready to run”. Products are made to order and “ready to run” locos are made/decorated by hand.
Scale Model Buildings: This is a UK company that supplies printable buildings in 1:450 scale for T Gauge. They have designed 30+ buildings in 10 different packages that you can purchase directly from their site as an instant download. They support credit cards, Apple Pay, and PayPal.
GS Models Supplies: A traditional local hobby store in Somerset, UK that also has an online store. This is the only place I am aware of where you can still find Electra Railway Graphics BR vinyl liveries for T Gauge. Electra stopped making them a while back so this may be the last available.
NOTE! Only mainland UK shipping, but they point out that if “you live outside this area” please contact them. If you live in the South West of UK (or visiting) you should stop by.