I've been doing some surfing and research for various Christian things in Gaelic. Here's a few to share:
1. Scottish Gaelic Bible: As far as I can tell, there are only 2 real purchasing options for those after a Gaelic Bible, one is a full Bible, the other a NT & Psalms with facing KJV volume. The ISBN for the full Bible is 9780901518101, for a NT/Psalms Gaelic-KJV the ISBN is 0901518271. These are the products of a translation made in the 18th century, with some revision.s throughout the year (so, I imagine, still in copyright).
2. Translation project: I'm very pleased to see that the Scottish Bible Society is undertaking a project to translate a fresh Gaelic version for today. You can read a few details here about the project, involving 3 translators. Using what I believe is a fairly good approach to financing, you can also sponsor a chapter for £35. I know I will (though with exchange rates, I am not sure I will be sponsoring many chapters.
UPDATE: The Gospel of John has now been translated, and is available from the Scottish Bible Society.
3. Highland Cathedral, St Columba (Church of Scotland) have a number of Gaelic resources. These include Ancient Creeds, the Westminster Catechism, Hymns, Psalms, and Prayers.
4. Gospel of Mark in Gaelic online. This shows up a few places on the Web. No accents, but great to have it available freely.