Hey Evelyn,
I do invitations, business cards, christmas cards, etc. all the time.
What I suggest is to export the finished piece from your layout program ( I usually design my stuff using Adobe Indesign) to a print ready pdf. Be sure to embed all fonts, spot colors, and leave about an 1/8 inch for bleed.
As Mindgraph suggested take the print ready pdf to Kinkos or another office place and have them print them. I have had good results using them. Sometimes I will upload the file to an online printing place. There are many reputable ones on the web.
Any questions, just pm me.
Jim