If you are talking about work of the order of $25K then you should be getting several quotes. You should be insisting that the service provider has appropriate trade licensing and their own insurance. Ask for a copy of the certificate of currency.
For very minor jobs it can be hard to find a tradesperson willing to do the job and you can be glad to find just one. Then the SC might just have to make a judgement about whether the one quote is reasonable or not.