I'm not a big numbers guy, but I'm excited about this year's pending lemon harvest. I bought my little potted lemon plant two years ago for $15.99. The first year I harvested 5 lemons. Then the plant grew a little bit. This year I've got 14 on the tree. Organic lemons sell for $0.99 at the local grocery store. 19 lemons x $0.99 = $18.81. I figure I've spent approximately the positive difference of $2.82 on water and fertilizer since I bought the lemon. So by my rough estimate this little tree just paid for itself.
I'm already looking forward to the smell of citrus blossoms, more growth, and more lemons next year.