I love, love, LOVE mounted pictures. But they can run $60 for a 20x30ish photo! Here's a way to achieve all of that for under $5.
Staples sells 17x11 photos for 98¢ ($2 for glossy or hard stock)... the next large color print size jumps to $30!!! Sooooo... I made some 11x17 prints, but I also wanted something bigger (you can get engineer prints, *black and white* for cheap, but if you want color, this is a good alternative.)
I used photoshop to split my 22x17 sized pictures into two different 11x17s so I could get my 22x17 (pictured below)
If you don't want to deal with the line going down your print, you can still do this with that $30 poster if you really want to.
Step 1. Tape the two bottom corners of your picture on your foam board ($3 from Walmart) so it will align when you spray the adhesive.
Step 2. Spray the adhesive and smooth out any bubbles- make sure it is all aligned! I used this adhesive* from scotch...(it's $17 dollars, but worth every penny! I didn't include it in the est. price because you can easily do 30 of these large projects with just one of these cans. * Some people use modge podge)
Step 3. Exacto knife it.
4. I used a charcoal pencil to touch up any white edge shown from cutting the paper (since I used a black board)
5. That's it!
You can also do this with wood for a thicker mounting (pictured below)