Here are some easy ways to reduce your costs to make the big announcement. Avoid heavy paper stock and engraving. Heavy stock requires more postage when mailed and most of what you send will be thrown away. Skip elaborate colors. They can be expensive.
Black script writing on white paper can be elegant.
Order only as many announcements you will need. Also, buy standard size invitations. Again, the large ones will cost more to send. For envelopes, consider doing your own embossing with a stamp. Or if you have a good computer and printer, print your own invitations and envelopes.