I use ceramic or porcelain tiles on which to bake my clay. Most importantly, have an oven thermometer to be sure your oven is accurate. Small ovens like toaster ovens can be up to 35 degrees either too cool or too hot. Always be sure you know how hot the oven is.
If I want no shine on the bottom I bake on card stock, like an index card with no lines on it. Or, if one makes something like an unusually shaped piece or beads they can put them in a bowl of corn starch or Baking Powder. I bury any beads and rinse them after they bake and are cooled. By burying the beads completely the heat will evenly bake the pieces and prevent scorching.
Sometimes I bake on a piece of Cardboard. At 275° F, paper, cardboard, card stock and baking powder or corn starch, or even Poly-Fil® will not burn.
I never bake on metal as it conducts heat and can, but not always will, brown the bottoms of my clay items.
As for a work surface, Walmart sewing centers have Fiskar® work surfaces, 12 inches square made of Acrylic. They also have grid lines and inch lines. I have one I take to guild meeting for a mobile work surface. Love it. BTW, clay works well with any acrylic.