Student colors are cheaper for a reason: they are made from the less expensive pigments (or mixtures of pigments) so the range of colors is more limited. In the cheapest brands, they've lots of filler in them too. As with so many things, you get what you pay for.
Student quality paints generally don't mix together as successfully (in terms of color produced, not consistency), nor are the results as vibrant as artist's quality paints. This can make color mixing frustrating. While using student quality paints is good painting experience, it doesn't give you the same color-mixing experience.
But on the other hand, you may be less inhibited using student's quality paint than with more expensive paints, and thus be willing to experiment more and simply try something to see what happens. Worrying about wasting your art materials is a sure way to stiffen up, to inhibit yourself, and usually ends with bad results (thereby fulfilling your fear that you were going to waste the paint!).
I believe in buying the best quality paint you can afford that still lets you feel you can play with it. You need to feel able to paint over something that's not working, or scrape it off, rather than desperately trying to keep it because of the cost of the paint you've used. I personally believe you're better off in the long run starting with a few quality paints and working on smaller canvases, than using a whole bunch of cheap paints.
Remember that with artist's quality paints not all colors are the same price. There are usually about five series or groups, based on the pigments in the colors. If money is a concern, hunt out the cheaper colors among the artist's paints. Look for paints labeled ‘hue’ or 'imitation', for example 'cadmium yellow hue'. These are made from cheaper modern pigments rather than the more expensive traditional pigments and are similar in color to the genuine thing.See Also: