If your front yard if flat you need 21 stones for each layer your would like to build. A typical retaining wall around a tree would require 3 layers. If your front yard has a grading, you have to see how many stones you need depending of the grading.
How much does it cost? As of 2010, the 4-day passes to Comic Con were $100 each. However, it increased as the years went by. According to WhenNerdsAttack.com, the 4-day pass with preview night costs $175 for adults and $87 for juniors, military and seniors.
Event tickets (or tix) are the currency that drives the Magic Online economy. Every ticket in circulation comes from the official Magic Online store (found in-game) at the cost of $1 plus applicable taxes (for me, in New York, one ticket costs $1.08 with tax).