Don't know your soil type but, we pull a shank with a 4 inch ball behind it, it will leave a tunnel that will drain your wet spot and not dent your wallet. We do it every other year and seems to work all right, the tile will plug with trash and dirt sooner or later
You would probably be good with your tile depth @ 18" w/ a sock and use 57 limestone size upto the surface or place 4" of topsoil on top so you don't have to worry about the stone moving.
'Crushed' limestone, although inexpensive, is a poor choice because it will begin to deteriorate over time and eventually begin to pack down and block the flow. 'Washed' rock" free of fines is a much better option.