There have been projects using the Bed, Bath and Beyond 8" (200mm) diameter candle holders and they have turned out nicely. There have also been those who have turned to old CRT tubes for the source of glass and those have also turned out well.
About any glass can be used for putting a nice mirror surface on so don't worry about that.
Other materials have been used, including but not limited to: aluminum, obsidian, steel and even casting surfaces with epoxy.
For the last, I saw a 8" telescope that had everything but the final layer of epoxy on it that weighed about 4 ounces! The destination was for a sensor on a satellite where weight was very important. The guy that had it on display said that the final figure was good enough to do less than 1/4 wave error at the sensor.