My prefix is wet, my suffix is cheap

Question

My prefix is wet.
My suffix is cheap.
My infix can be expensive.
As a whole, I am happily devoured.

What am I?

Answer 1

I think you are a

Marshmallow

My prefix is wet.

Marsh

My suffix is cheap.

Low

My infix can be expensive.

Mall (or perhaps All)

As a whole, I am happily devoured

Marshmallows are very tasty.

Answer 2

You could be:

WATER CHESTNUTS

My prefix is wet.

WATER is wet (by definition!)

My suffix is cheap.

NUTS (often peanuts) are often used as a metaphor for something costing very little ("I got it for peanuts!").

My infix can be expensive.

A treasure CHEST is a valuable thing indeed!

As a whole, I am happily devoured.

Water chestnuts are delicious in many Asian dishes! Nyom, nyom...