Where are the cheapest hawkers, foodcourts or restaurants in the CBD area?

Dont worry, there are hawker centres, food courts and coffee shops even at raffles place! I'm sure you'll have colleagues that eat cheap lunches too and they'll probably bring you ard. Some places for cheap-ish food in the CBD:

Hawker centres: telok ayer mrt, amoy st and maxwell rd, lao pat sat

Food courts: Asia square lvl 2, shenton house Lvl 2, Clifford centre basement, Arcade level 1

Coffee shops: Philip street, McCallum street

Also good to pack your own meals. Make it lovely and healthy any way you like.