I was nervous about using an online vendor, but I could not have been happier with my invitations. We received so many compliments. The cardstock is heavy and high quality, there are many designs available, and you can see what your invitation will look like online with your own wording before you order it. They will also send you a sample before you place your final order.
One of the customer service reps advised me to use regular ground shipping rather than paying the hefty overnight shipping fee, since she knew I would receive my order within two days based on the location of the printer. Since I was both in a hurry and on a tight budget, I really appreciated that courtesy.
I also bought my thank you notes from them, and they were lovely.