We don't publish a flat number here because roller count, roller type, and whether the track needs correction all move the price, and we'd rather quote your actual door than post a figure that doesn't hold up on site. What we can say: steel rollers cost less per unit than sealed nylon, and a full-set job costs less per roller than replacing them one at a time on separate visits, so if you're already hearing noise on more than one roller it's usually worth doing the set.
Given the income profile in Bartlett, we get more requests for the nylon upgrade than we do in some other parts of the service area - not because steel doesn't work, but because owners here are more likely to ask for the quieter option outright.