"One day we'll float....take life as it comes" PJ Harvey
I first started out fusing with float glass. It's cheap, it's plentiful (ask for scraps at your local frame maker's) and it's easy to cut. Float is called "float" because it is poured onto a bed of molten tin within a furnace and then machine rolled. It is totally flat and is used for window panes and picture glass. It's disadvantages are: it takes longer to reach full fuse temperature than most other glass, it sometimes becomes cloudy or milky during fusing and it can send splinters out when grinding. If you want to avoid cloudy glass (devitrification) then spray it with A Spray before it goes in the kiln and wear those goggles when grinding! Tempsford Glass sell Spray A.
At first I fused copper wire and copper sheet between two pieces of float but then I discovered coloured float confetti. Now coloured float is widely available (only in transparents at the moment) which makes it cheaper to create dishes and coasters than using Spectrum or Bullseye. The good news is that dichro coated float is also available, although it's not as nice as dichro coated Bullseye.