Of course you need a nice, long red carpet for your event -- so your guests can strut down the length of it in style. Roll the carpet out as far as it will reach from the entry to the event locale. If you're throwing the party at your house, run the carpet all the way from the curb to the doorway. If your party takes place at a rented venue like a luxury hotel ballroom or theater, run it from the entry point to the party room.
You can buy a red carpet runner at a local remnant or party supply stores, or you can find one online. They aren't too expensive; we found a 24-inch-wide by 15-feet-long runner online for about $9. Depending on how long you want your red carpet to be, you'll probably spend between $10 and $30.
To make the walk extra special, rent velvet ropes and posts to place on either side of the carpet. Find a local source to avoid shipping costs.