If I remember rightly the main cost incurred in refurbishing the Shuttle was the checking and replacing of the re-entry tiles as they never lasted as long as anyone expected and the slightest failure would prove catastrophic to the vehicle (see STS-107 Columbia - though the damage to the tiles was caused in orbit).
Oh, and there were a lot of them. Over 20,000.
I recall only the OMS and the Main engines needed to removed, stripped and refurbished.The OMS rockets were built in modules and could be replaced quickly.
Rocketdyne built 45 RS-25 engines and only had one in mission failure throughout the lifetime of the shuttle. Considering they were gimbal-mounted and throttleable that's astounding. Anyway even with the full fleet of four orbiters full built, there would be 33 engines either being refurbished, in the test phase or certified ready-to-fly.
If it wasn't for those tiles, the shuttle turn-around could probably been much faster. But it's not really fair to say components being reusable isn't effective, or safe, or cheap. As Killing_Time says, there's plenty of data around on the RS-25 project - 405 individual engine missions to be exact.
The main things that killed the shuttle as a resuable space truck was that its hand-gnawingly expensive to get humans into space, meaning that each shuttle launch was $500m+, and that the complete system simply didn't go high enough, or carry enough payload, to make the economics work.
Falcon 9, however, can heft a payload to much the same altitude as the Shuttle did, and bring the vast majority of its lifting ability back to earth safely for refurbishment. The 9 engines on Stage 1 are largely identical to the single engine on Stage 2 so the entire system uses one engine design (Shuttle had two, Apollo had four). A lot of the control hardware is off-the-shelf gear running open source software. All of this brings down the cost-per-launch and the cost-per-kilo to launch.
Dragon support launches for the ISS cost Nasa $133m each under a fixed price contract. Falcon 9 launches are currently $69.2m. If SpaceX can reuse large parts of that first stage, perhaps $30m a launch is achieveable - that is extraordinarily cheap.
If Bezos gets his New Shepherd to the same level, competition will drive the commercial unmanned prices down. If the Falcon Heavy can shift twice the payload to twice the height that 9 can, that'll drive the prices down. if the Dragon Crew capsule gets approval that puts SpaceX in commercial competition with RKK “Energiya” (Soyuz) which will bring the manned launch prices down.
This is the start of something great.