CMU offers cheap canteen grub at every facility, but Romsak Market (everyone calls it Fai Hin) has much more variety and better food. A stall in the front sells Japanese curry for 40b, the fruit shakes are great (tip: the best are from the guy who looks like Barack Obama) and every other type of cheap Thai food you can think of is available somewhere. Most stalls tend to run out of ingredients before 8pm, so get there early. Remember to take your dishes to the back!
Romsak can be a bit difficult to find – go towards the mountain from the CMU clock tower, take the first right and follow the road. If you’re there before the sun goes down, order to go and take your dinner up to Ang Kaew reservoir.