I'm surprised the West Side Market isn't busier. Its a wonderful sensory experience! So much to see, smell and taste! There are crepes cooking on one end, fresh pierogies on the other, roasted cinnamon almonds sold by weight, yummy dried fruit, fresh produce, fresh meat....and the list goes on.
Skip Giant Eagle and just go to the market! So much more fun, it'll save you some money and you get to support the local vendors. Can't lose.
Bring cash! Small bills in 5's or 10's. Also bring some cloth bags to throw your stuff in.