If you buy shoots, you can have your cake & eat it too.
Carefully pinch or cut off the leaves, and cut off the new growth stem & all down to the 3rd or 4th leaf (being careful not to damage the remaining stem)... then cook & eat the leaves. Trim the thickest part of the remaining stem down to about 6", and place the stems in a glass container of water so that 1/2 of the stem is submerged. Put the container in a bright location; watch for & remove any stems which begin to rot. The stems will root quickly, and can be transplanted to their permanent location.
While I start my kang kong from seed each year, I plant the stems from the first harvest to increase the yield later in the season.