Why such a large spread for timing belt replacement costs for different cars?

I have a 2003 Volvo and the garages, a few that I have asked, say $1100. My friend has a 2001 Ford, and online it says $200-300. Why such extreme price differences?

Added (1). My other friend has a 99 Toyota and a 2005 Toyota and was quoted $900 and $1000, respectively.

Added (2). 2003 Volvo S40 (1.9). The last garage that told me was the one I always use and it very reliable and honest. They are a family business, and I know the cousin. I imagine that the quote is for replacement for all the stuff you should do at the same time.

Ugh. I was just psyched that I had money for new tires and then would be caught up. Sigh. Oh, Murphy's Law… How you vex me.

Every engine is different and the time to replace a timing belt can vary from a few hours to 10 hours. You didn't tell us the model so we can't look it up.

But you can't compare the repair costs for your Volvo to another car. They're all different.

I have an 04 S60 2.5 turbo and had the timing belt replaced for 1000, an independent volvo specialty shop quoted me 1600. If is a quality shop and they do all the extras that is fair price.
The timing belt is hard to get to and for an expert shop it takes around 6-8 hours of labor
When doing this job you want to replace the water pump,
This Kit contains: The Timing Belt, Replacement Sticker, Tensioner w/ pulley and Idler Pulley with bracket, water pump. The kit will be $250, proper new coolant is 40.
The 200-300 quote seems impossible low. Maybe for the most basic ford?
It really depends on how long it takes to take the engine apart to get to the belt.
I had the timing belt go out on an 02 Neon, it is hard to get two and the engine has to be jacked up and down 3 times, motor mounts have to be removed, etc. A national chain store quoted me 1500. I got it done another shop for $900 including parts and the guy said it took him longer than expected.

Lots of things in the way to do a timing belt, but $1,100 is highway robbery.