I would start by going to the copy shop. The one I use has papers you can look at, so you can get ideas and have the paper in mind when you design the invitation. They can tell you what your options are.

Have fun!

It depends on the type of business you use. If you use a copy center, you will need to use their paper.

Many printers who work with small businesses fill in by printing invitations and similar items. If you choose a printer, most will allow you to bring in your own paper. They can also print with colored ink and with a raised print (thermography). The price will be a little higher than a copy shop, but you will get a much nicer invitation.

Most copy shops want you to bring them a digital file on CD - or sometimes you can just email it to them. Usually they want a TIFF file or something, but they might be able to make a PNG or JPG work (I'm not sure if JPG is high enough quality though).

As for paper, you'll likely have to choose from their stock. But they should have a lot of options in terms of colors, textures, and weights to choose from.

Hope that helps - good luck! We DIYed our invites and looooved them. It was a lot of work but I made up the design on our computer and printed them off one by one on my parents' photo printer. Then we added ribbons, embossing, etc. They were pretty !