From: Kath

You nailed this one!

However, if you don't have or want some ingredients/substitutes, just leave them out. Watermelon plain, or with salt is perfect. With cheese or nuts, divine. With herbs as well, other-worldly. Still, watermelon by itself is something most everyone loves, but the extras make it special.

My local Middle Eastern store has 6-8 varieties of feta--I prefer a salty, crumbly one for this recipe.

Some balsamic vinegars are very thick (and expensive), so your method of reduction before buying stuff that costs a lot is an important tip. I tried a sampling of balsamics and don't think an expensive variety is necessarily better than a reduction, at least not for a pricey sum one might pay for aged balsmics.

Something else I'd like to suggest is that seed-in watermelon is often less expensive, and with just a bit of effort, you can have the seeds to plant or roast.

http://www.ehow.com/how_2122230_preserve-watermelon-seeds.html
http://egyptfarm.blogspot.com/2008/07/eating-watermelon-seeds.html
http://www.tucsoncsa.org/2008/09/15/indian-bean-soup-with-roasted-watermelon-seeds/

I'm a firm believer that seeds are one of the most important foods as they are the kernel of all the goodness in what will grow, so I urge folks to save seeds from heirloom produce and learn to eat sprouts (radish, lentil, broccoli, alfalfa, etc.)--learn from sites like http://www.sproutpeople.com/index.html.

Don't forget, watermelon rinds can be pickled, e.g., http://www.foodista.com/2008/07/26/pickled-watermelon-rinds/, http://projects.washingtonpost.com/recipes/2008/08/27/pickled-watermelon-rind/ or composted.