My philosophy is buy quality once and take care of it until it dies.
I have an old CRKT liner lock knife that I've carried on and off for over 12 years easily. It's not the most ideal knife, but it was cheap as fuck (cost me under $25) and more than gets the job done. Now that I find myself using a knife on a more frequent basis, I wanted something more substantial as far as blade size/length/thickness are concerned, as well as the handle size.
If you are prone to misplace or lose things, save yourself the headache and just buy something to get you by. I'd personally prefer a CRKT over most Kershaw and most SOG knives any day. That's based on my own experiences with those 3 brands and after having a wide variety of products from each brand in my hands.
If you do go the cheap route, avoid the assisted knives at all cost; they are just not worth it. If you get the chance to play with a few, grab the blade and try and wiggle them around. You should see a huge difference between models, and brands right away. I personally wouldn't purchase a knife that has a ton of play in it; but that's just me.