To me, that is the beauty of this medium, it is done so many ways. With all your art exposure I am sure you have seen that some folks nearly only use magazine and/or book photo bits and arrange them different ways. Lots of folks include markers of many kinds to add fun details to whatever paper arrangement they have made. The majority of collage artists that encourage folks to play in it, often say "use what you have", junk mail, any papery art supplies you already have, tissue paper, bits of wrapping paper, receipts, anything you clean out of your files if you still keep paper, anything really, if it is paper, it counts. Lots of folks also include things like twine, ribbon, bits of leftover lace and the such too. There just really are no boundaries. So whatever you have will work, because ... it just will. I didn't start out full blown like I do it now, I started out using what was here. It just grew to what it is now because I play in it every day.
I am not sure at this moment what I might choose to do on the selling side. Before collage, I sold some paintings that I have done for years, but I never ventured to sell online. I wasn't sure when I started painting that I wasn't supposed to give my art away. I have done some of that too! I just make it up as I go along, but there is a half a thought about taking it further one day. Like you said about the packaging and shipping and the such, there are many things to consider before staring something like that. I don't know if you have ever looked at the DPW site or not. It is not the booming place like the big sites are, but for about $13 a month, you can put your art there and sell or directly folks to your Etsy account or wherever you sell if you sell on another site. There are lots of kinds of art there from very good artists to not so great. You can put in "collage" and see what some folks have put there. I don't know how successful of a place it is for artists, but it's and inexpensive way to show art while you learn to test the waters.
Hope you have a good week and a safe trip home.
Thanks for coming by.