My basement floor has lots of hairline cracks that seep water after a hard rain, I painted a waterproofing sealer on my walls years ago so they have no problems. Just the basement floor.

can anything be done that will seal those cracks that will not be
extremely expensive?

A friend suggested drilling a couple holes in the floor to releave the water pressure in the floor said if I had not sealed the walls so well it would be leaking through the walls so the water has no where else to go other than up through the floor.