Custom invitations can run around $1,000 for 100 invites - yikes.
DIY can look cheap, but if you follow a few simple tips, it can make it that much more elegant.
Basic rules of design that you can use for invitations.
1. Incorporate a hierarchy. Don't make everything one size. Make one element stand out, a sub element, and smaller details in smaller type.
2. Use white space. Don't fill up the entire invitation just because there is room. White space not only leaves breathing room, but can give a very modern, sophisticated feel.
3. Use shades of grey. The softer contrast [versus pure black and white] is more elegant.
Here are a couple of examples I made rather quickly. The typefaces are free for download at dafont.com.
Download Old Script typeface here.
For the information, I used Baskerville. Sanford is a free, similar type face.
Download Miama here.
Use Century Gothic for the text.
If you are unsure of downloading typefaces, this is a great option. It simply uses Garamond with italic variations, which is available on all computers. It was a typeface designed in the 16th century. It is considered a classic.
Fonts strongly not recommended.
For basic, yet elegant stationary, here is a great example from Target.
Wedding Invitation Kit White Pearl 50ct $29.99
See more on how to word an invitation.