Lately I've been enjoying a variety of wines from Rex Goliath. The Pinot Noir, Merlot and Cabernet Sauvingion are terrific and the price is right. I'd go with the Pinot Noir and you should have no trouble finding it for under $10/bottle. I can't be of much help with white wines, sorry.
If you want to spend a bit ($12-18) more I can make a few other recommendations on red wines.
Another thing I would highly recommend is to see if there are any wine retailers in your area. If so, they most likely hold a wine tasting every month. This is a very good way to taste a variety of wines before you buy them. Since you've got some time before the party you should be able to attend a few tasting.
Have fun!
If you want to spend a bit ($12-18) more I can make a few other recommendations on red wines.
Another thing I would highly recommend is to see if there are any wine retailers in your area. If so, they most likely hold a wine tasting every month. This is a very good way to taste a variety of wines before you buy them. Since you've got some time before the party you should be able to attend a few tasting.
Have fun!