I'm here to report back about our visas. We got one month tourist visas, I believe if you pay more you can get other types. This service is only available to residents.
I spent about a week emailing the Double Capital people to make sure we had everything sorted, and also to check costs etc. They reply pretty quickly most of the time.
What we needed to provide: a) Invitation application form (via email)
b) photos/scanned copies of ARC, Passport, Payment Receipt
c) Detailed Itinerary including all train/flight numbers etc (they
asked for actual bookings but I just gave this instead)
d) Completed visa application form
e) One passport photo
f) ATM Transfer receipt
g) Photocopy of ARC and Passport
The cost of the visa varies depending on Nationality. The invitations/visa support letters were NT1470 each. Postage was NT120. Visas were NT2160 for Australian, NT2736 for British.
Here is a step-by-step guide to getting a visa (if you're in Taipei you can go in person):
1. Email Double Capital at the address found on their website, checking what documents you need to provide and the total cost for visas, invitations, postage etc.
2. Do an ATM transfer of the full payment for everything, scan/take a photo of the receipt.
3. Email the transfer receipt, visa invitation forms, photos of ARC and Passport, and itinerary to Double Capital.
4. Put your passports, completed visa forms, photos, itinerary, transfer receipt, photocopies of ARC and Passport in an envelope and post/courier to Double Capital.
5. Wait - we emailed them to check everything had arrived, and didn't hear back until we got a call from the postman saying to come downstairs and sign for a letter.
We applied on a Monday, and got our passports with visas back the next Wednesday.