Here’s a great resource for figuring average remodel pricing by the type of job which can be broken down by geographical location- http://www.remodeling.hw.net/2013/costvsvalue/national.aspx
These are some rough cost estimates to replace the fixtures and finishes in a small bathroom, with a licensed, insured, reputable contractor, in L.A.:
-
For very basic finishes, about $200-$250 per square foot. More if you want custom touches, less if you go with one of the companies offering a standard package.
-
For upgraded but not luxury finishes, $300-$400, with variation up or down according to the contractor.
-
For luxury, the sky is the limit.
Those numbers are a starting point. If you want a tub or a toilet moved, or if there’s structural damage from a leaking shower, the costs can be much higher. The difference between basic and luxury finishes is not just the price difference between the materials - the luxury materials will be installed to a higher standard, by more expert and therefore more expensive personnel.
As a contractor in the greater Los Angeles area, I can tell you that bidding “by the sqiuare foot” for a remodel is ludicrous. It really depends on materials chosen - for instance, you can get a prefab vanity for $500, or a custom one for $5000. You can choose tile that’s $1.50 per SF for your shower surround, or travertine marble that is $15 a SF. The average cost for a bathroom refresher, using existing plumbing outlets (meaning fixtures are being changed, but plumbing is not being moved or repiped - using EXISTING outlets, vents and drains) is around $10,000 - $12000 including materials, but I have seen them go as high as $45000, and have done a basic hall bath for as little as $6000.