Cheap wine glasses are an absolute requirement for any serious (but informal) social engagement that you may throw at your house or apartment. They stand as a very important replacement for good, expensive crystal or high-quality glass wine glasses and cheap plastic glasses that you can buy five for a dollar. Why? It's simple.
It is unfair of any host to cause his or her guests to be concerned about dropping or breaking expensive glassware as they mill about and mingle in their perhaps semi-inebriated states of alcoholic euphoria. Indeed, if you're even a little concerned about the long-term survivial of your glassware, it's going to impact your ability to throw a good party. Instead, you should provide glasses that are elegant without being so expensive that you couldn't, without lying tell your guest, "Oh, don't worry that it broke." Your guests will appreciate this, and so will you.
On the other hand, this can be taken too far. Using plastic glasses is a serious social no-no. Passable glasses are so inexpensive that they should really be a minor portion of the overall cost of the party, and it is highly likely that they will survive for quite some time, thereby reducing their per-party cost to almost nothing without making you look like a cheap bastard.
You may seek out cheap wine glasses at your local discount stores. They should be under a few dollars each, and can likely be found for $1.50-$2.00 each at the time of this writing. Buying ten or twenty for your guests will be pretty inexpensive in comparison to any wine that is good enough to feed to them.