InLimbo, I do well, sometimes, at TJ Maxx (Ross, HomeSpace, etc...any store that sells discounted designer items and has housewares, too). Usually around $5 for DaVinci syrups. I've tried non-name brands and they are usually very weak in taste and sweetness.
I do extremely well, when I can't get them at TJ Maxx, by getting my syrups (and other items, usually Eat Well, Be Well things...) at www.netrition.com
I can't say enough good things about them. The bottles arrive in a huge cardboard box lined with 2" thick styrofoam on every side, and cardboard dividers between the bottles. I've never had a broken one. They ship chocolate in the summer with ice packs (it's an extra charge...think it might be $3?), and they ship quickly. I live near them, so I get my items the next day! They send you a free t-shirt/tank/water bottle/etc. of your choice if you spend over a certain amount...not sure what the amount is, but I've had the offer every time. They've basically made up most of my gym wear at this point!
Good luck! I love working with syrups...they are so versatile and helpful!