Opinels are great knives for money! all of them I know in france had an Opinel as first knife! I recently buyed a number 8 to my son and at the same time I took a number 9 for and stucked it in my Bug Out pack. as extra knife!
another great inexpensive folder that can be RAZOR sharp, the DOUK-DOUK!
Try a medium or large douk-douk in your pocket for 2 or 3 days and you will allways carry one! Fred Perrin learned me about the Douk Douk and once he showed me a good trick! As he said, a Douk-Douk is so inexpensive that it doesn't matter if you ruin it, so if you need a fixed blade, take a multi tool and press the handle together so you have an improvised fixed blade
http://www.geocities.com/Hollywood/Set/2292/doukdoukrev.htm