Novacolors are actually considered inexpencive...anyway even if you buy the most expencive set - it only takes a "few cents" of color to paint...
and you do not need too many colors.. 10-15 is more than enough - you mix the shades and tones...
so 50-70 dollars should get you setup
in my opinion looking for the cheapest paint is like driving over the speedlimit - you can save 5-10 min but risking to waste an hour getting a ticket in the best of the bad endings of speeding.
The same way with paint - the cheapest set(10-15colors) will run you about $50 and good quality (like nova) will cost $10-15 more but you are spending hours looking for a cheap one. Does your time worth less then $10 per hour?