For some girls the STD and invites are important. I'm at the Invite stage right now. Figuring out paper needs for 50 invites, if I go through www.cardsandpocketsstore.com for materials, it will cost approx $180 + extra embellishments + postage. I'm sure I can find cheaper paper, but I'm figuring about $225 in materials then I print and put them together myself. I may or may not go this route.
I paid approx $23 + 12$ in postage for my STD postcards. I had them done at VistaPrint. Quality wasn't the best, but friends and family thought they were cute. It was basically a way to get people to our website for more info.
What I found is you can spend $30 and you can spend a zillion dollars.. it's all about what you care most about and your budget.