I looked up some cheap folders I bought. The cheapest decent folder I've bought is $23 on Amazon.com.
http://www.amazon.com/Smith-Wesson-CKG105-Extreme-Folder/dp/B0014VGJFO/ref=cm_cr-mr-title
I've bought cheaper folders, but none would I plan to use on purpose.

A quick upgrade to a cheap knife is take out each screw, drop in Blue Loctite, and screw back in. Also, buy a decent sharpener. You will have to sharpen more often. I personally don't mind. Sharpening more often allows me to keep up with my sharpening skills, and I'm not nervous about sharpening a cheap knife.
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If you're reading this, it's too late.