So I just finished making my first mirror and I am extremely pleased with the way it came out!
This project took me quite a while from start to finish and I learned a lot from this build.
Monitor is 23" and takes up the entire mirror
For the mirror I used 3/32" inch glass with Gila privacy film
Raspberrry Pi - $39.00
Monitor - Free (Letgo)
Gila Film - $29.55
Wood - $11.33
Glass - $6.28
Wood Glue - $3.97
Stain - $4.48
Metal Brackets - $2.27
Overall, I am really happy with this price as I tried to make this project as cheaply as possible, so under $100 is really good.