The cheapest and most effective microwave cleaning products are available in the average grocery store. Many people recommend using lemon or vinegar with water to create steam that loosens grime inside a microwave, making cleaning as simple as wiping the inside of the appliance with a soft cloth.
To use lemon, cut a lemon in half and squeeze the juice from both halves into a bowl containing half a cup of water. Place the whole thing into the microwave, and turn it onto high power for three minutes. Once the timer has stopped, continue to leave the bowl in the appliance for another five minutes. Then remove the bowl, and wipe the inside of the microwave clean.
Those using vinegar should add 2 tablespoons of vinegar to 1 cup of water in a bowl. Place the bowl inside the microwave, and follow the steps above. To prevent the appliance from smelling like vinegar, add a drop of essential oil to the bowl before running the microwave.
Whether using lemon or vinegar, those who encounter stubborn clumps of dried food residue are likely to remove them by dipping a cloth into the bowl of lemon juice and water or vinegar and water and applying it to the spot with pressure.