I'm not sure about the origin of limoncello (I do know Danny DeVito has his own brand now) but the Amalfi Coast is the best place to drink it because of the extraordinary quality of the lemons there. I've spent many hours sitting on the cliffs sampling the local wares. In Puglia, homemade limoncello is commonly served after a big meal. You can make any kind of "cello" you want, including orange, cherry, and spiced cellos. Here's a recipe for the basic limoncello.
1 750ml bottle of Everclear
8 medium-sized lemons (get the best you can)
1.9 cups of sugar
750ml of water
1. Get a large jar that will fit two liters or more. Peel the lemons using a regular ol' lemon peeler. Try not to get much of the white stuff, i.e. pith, because it makes the limoncello bitter. (If you want to be resourceful, squeeze the lemons and make lemon juice. Freeze it or keep it in the fridge for other uses.)
2. Put lemon peels into your jar. Add sugar, booze, and water, and stir rigorously. Not all of the sugar will dissolve. Continue to stir once a day or so for a week. Store jar in a dark place.
3. The Tweeking Process: After 30 days, taste your limoncello. Sometimes it is too bitter or too alcoholic or it needs more lemon. To fix this, just add more lemon, water or sugar, but don't go overboard: The only way to make it less watery or less sugary is to go out and buy more Everclear. Test your limoncello again after 10 days, and if it tastes the way you want it, take out the lemon peels. Store for another 30 days, then put it into bottles, put the bottles into the freezer, and drink when chilled.
Note on Everclear: Everclear has an alcohol proof of 200%. It is the closest thing we have to "plain" alcohol, which is a common product on Italian grocery store shelves (usually right next to the soft drinks), because it is flavorless. Ask your local liquor store clerk for further help.
Note on Saving Money: This recipe makes just over 2 bottles of limoncello and the total cost of ingredients should be around $18. One bottle of limoncello typically costs $35 at a store. You do the math.