The cost gap
Fixr's installed-cost breakdown puts a prefab acrylic surround at the low end, a one-piece fiberglass unit a step above it, and a fully custom ceramic tile shower highest of the three by a wide margin.[1]
Roughly the same split shows up in independent data: prefab stalls land around $2,000 to $6,000, while custom tile lands around $6,000 to $12,000 for a standard three-wall shower.[2]
The gap is almost entirely labor, not material. A prefab unit arrives ready to set in place; tile goes up piece by piece over a waterproofing system that has to be built correctly before the first tile is set.
Who does the work
A prefab installation is mostly plumbing work: setting the base, connecting the drain, and hooking up the valve. A licensed plumber can typically handle the entire job.
A custom tile shower brings in a second trade. Tile and stone setters, who build the waterproofing bed and set the tile, earn a median $23.52 an hour nationally, and their hours make up a large share of a tile job's labor cost.[3]
Labor runs 40% to 60% of a tub-to-shower conversion's total cost either way, but a tile job simply has more billable hours behind it.[4]
What each option trades away
A prefab unit is faster and cheaper, but it limits your layout to whatever sizes the manufacturer sells and gives you fewer options for a bench, niche or custom drain placement.
A tile shower can be built to any size the framing allows and supports built-in features like a niche or bench, but it takes longer, costs more, and depends more heavily on one trade doing the waterproofing correctly the first time.
How the permit and inspection load compares
A prefab swap that reuses the existing plumbing location often clears with a single plumbing inspection, since the walls arrive as finished, sealed panels with nothing behind them to check.
A tile shower usually adds a waterproofing check before tile goes on, because that membrane is the one layer an inspector can't see once the job is finished. Ask whether your city schedules that inspection separately, since scheduling it late is a common source of delay on tile jobs.
How to decide
If your priority is getting a working shower back fast at the lowest reasonable cost, a prefab acrylic or fiberglass unit fits that goal directly, and a single licensed plumber can usually deliver it.
If your priority is a specific size, a built-in bench or niche, or a look you can't buy in a manufactured panel, a tile shower is the option built for that, at the cost of more time, more money, and more trust placed in the tile setter's waterproofing work.
A middle path exists too: some manufacturers sell tile-ready backer panels that install faster than a full mortar-bed system while still accepting real tile on the surface, narrowing the cost and time gap somewhat without matching either extreme.