Hi! I've been bored online tonight and I found a few websites that sell glass bottles.. maybe you and your FI would like these. They are relatively inexpensive...you could fill them yourselves, and possibly even print some personalized labels or stickers for them on your printer, and then put them in a cute bag.
These are 8oz with screw caps, but also have corks available:
http://www.bottlesandmore.com/Product.asp?ProductID=6539And these come in all different sizes/colors:
http://www.freundcontainer.com/product.asp_Q_pn_E_4900B01_A_cn_E_22You could make them look something like this: (I love how they say "the perfect blend".
If I'm calculating correctly, if you have 203 people, and you give a set to each couple, it would work out to about $300 for the 8oz bottles, plus the cost of the vinegar & oil (which you could buy in bulk), and a couple bucks for the labels/bags. Still works out to less than $2 per bottle. That's less expensive than my favors and I've just doing Hershey kisses in a clear bag witha ribbon!