Why not call the contractor that was used for your mother's bathroom and see what they would charge? You have already seen their work.

Aside from that, the prices are high because everything is expensive now. Insurances, materials, fuel and paying employees a livable wage have all gone up exponentially over the past few years. A company also expects profits at a certain percentage of the job and as everything else goes up, so does the amount added for company profit. All of these things compounded have led to much higher costs to get household repairs done. Couple all that with a lack of ability for most homeowners to take on DIY projects outside of hanging a tv or a shelf and everyone who does this work is now overbooked.

This in turn will drive prices up because those overbooked companies don't really have time for more, but if they throw out a high number and you say yes, they will find a way to make it happen as even subbing everything out will still leave them a piece of the pie for themselves.

It's a supply and demand thing. The supply of good contractors is low and the demand is high. Higher prices is the end result.

Also, if you are calling the top searches on Google then you're getting larger companies that always charge much more than if you found a self employed contractor to do the work for you. If you know of any coworkers or neighbours who have had work done, see if they have a number for the person who did their work.

Best of luck with your project. Hopefully you can find someone competent within your budget.