After considering my option for outer envelopes I decided to go with jampaper.com. After you find them on Facebook, Twitter, or Pinterest, they offer you a $5 off $25 or more purchase, making them the cheapest option. I ended up paying $39 for 100 envelopes! I took a chance and just ordered the dark purple envelopes without ordering a sample since their samples weren't cheap. We'll see how it turns out.
I can't wait for these to come in. We really have to get working on invitations. Our goal is to have them in the mail by the last week of July (so soon!).