We've been serving Domaine Ste. Michelle for a while at parties, It's a great bargain sparkler at $6-8.
A few months ago we picked up Comte de Galeyran at TJ's (for BayCon, I think), a $5 Limousin sparkler from France (from Limoux, not Chapagne, which is how it can be French but not Champagne). We quickly dubbed it "Comte de Gallifrey," and were planning to get more to bring to the convention of the same name, but no. Total stinker. Nasty. People drank it, but not me.
The other night we found, though, Trader Joe's Blanc de Blancs at $4. It's real French Champagne and it's cheap. Took a taste, and it's pretty decent. The Domaine Ste. Michelle is worth the extra few bucks at the beginning of the night, but saving $30 or $40 on the last case of the evening is worth the trouble.