get nice frames for .10 to .25 otherwise it is about 1.00. sometimes if you show up at the end of a sale you can get a whole box for $1 to $2. i use a white museum quality mat and foam core and finish it nicely with acid free tape.
i always sign and date and put a personal note on the back. a part time job with a custom frame place will give you lessons on mat cutting plus access to a mat cutter and materials cheap plus a little income to pay for your supplies. do well and build a relationship with the owner and you can go 