It depends on what you purchase for fixtures, the tie ins for the plumbing and the unforseen issues that always come up. but that is usually the # for the parts...diy.Then add on from there with what degree of product you will buy.
To spend less, Look around for stuff folks have purchased but are not going to use, just remember there is no return policy.
And sometimes DIY can cost more...like when you screw up really big and crack the tub drain flange.
Good thing they can repair them nowadays as one of my customers had to find out the hard way.
As always, just do your homework and write your list of things to purchase , and what you can do yourself. That will help you with the real # you are looking for.