So I did some searching online for supplies. I have decided that I would like to send 8×10 photos to have signed. I think the safest way to mail them is in Ultra Pro Toploaders.

I found them on Amazon. I think if I use these I can buy some cheaper envelopes and not have to worry about the SASE fitting in the original mailer. At the time that I am writing this, these toploaders are 19.99 for 25 (.80 ea.).
These seem to be a cheap way to go to mail out the 8x10s:

…but I’m not sure trying to fold one to include as the SASE is a going to work all that well (but it could I guess). I will continue to research. I do not want to jump into spending money until I know Ive found the best deal.