Depending on the shower, a third or more of the cost is the tile installation for a fully tiled shower (walls and base including niche). A good tile installer is becoming more rare and more expensive. The waterproofing system we use also accounts for about 15% of the cost as well. There are also custom glass doors included in that as well I believe. We've seen material costs from copper, lumber, abs and a range of other construction supplies increase multiple times in the last 12 months. A 2x4 has more than doubled in that time. We are constantly quoting and seeing the numbers move on a regular basis is eye opening even for us and I've been doing this 17 years. 3 years ago, it was $8,000 for the same work.