There are many ways to have an inexpensive wedding, using very cheap wedding invitations will make a good size dent in that budget.
I know, I know, when you think of a wedding, very cheap isn't the first thing that comes to mind. Just because you don't want to spend a lot doesn't mean you can't have what you want. It will only require a little creativity.
Now you have to consider that cheap doesn't mean free. Although the template is free, you will still need to purchase the supplies to make the invitations. But don't worry these will still be inexpensive wedding invitations.
You can purchase the supplies from the web, many of the free template sites also sell supplies. Or you could probably find all that you need locally. Try the local craft or scrapbooking supply stores and you should find everything that you need.
The most important part is the creativity. Think about the message you want to convey or the theme of your wedding and that will start you off.
Do you want formal of casual? Bright colors or monochromatic? Flowers or ribbons (or both)?
Just let your imagination go wild, start with a wedding invitation template and purchase locally if you can. Even better, leave enough time and you can shop the sales. You will be surprised how beautiful and affordable your wedding invitations will be.