Both Premier League clubs are expected to make moves for the 18-year-old left-back in the January transfer window.
Following the 2-1 defeat to Swindon on Tuesday night, Saddlers boss Smith said the talented youngster would not come cheap.
"It's going to take a hell of a lot of money to take Rico away from this football club," he said.
"If I were to liken him to anyone it would be a young Ashley Cole and it's up to him how far he can now go in the game.
"I've recommended him a couple of times to the England Under-19s because, if there's a better left-sided player in the country at 18 years of age, I'd like to see them.
"If he keeps developing and keeps his feet firmly on the ground - his parents will make sure of that - then he'll go the right way."