I guess the best way to start is to explore some options for remodeling a bathroom.
Option 1 being the most expensive would be a full gut renovation of a bathroom. A standard 5' x7' bathroom in NYC using basic builders grade material would run in the range of 10-15k just for labor. As you begin to pick out more expensive tiles/patterns and fixtures the price for the material as well as the labor goes up. Robrn cabinets, Toto toilets, marble, onyx etc, etc.
Another option to lower the cost is to leave the bathtub in place especially if it's an old deep cast iron tub. If its dirty, scraped, gauged or just plain disgusting you can have the bathtub refinished. A liner is another option. Bathtub refinishing done right will make your tub look like new.
Going a step further to save even more would be to regrout tiles that are in otherwise good condition. You would be surprised to see the difference after a tile wall and tile floor has been regrouted.
If your tiles are beyond cleaning and grouting but are salvageable refinishing the tiles is a good option. Refinishing tiles can save you a lot compared to replacement. Also if individual tiles are damaged or missing its possible to refit new tiles as long as the sub structure behind the tile is in good shape. Refinishing also offers the ability to change the color of your tile walls as well.
I would not recommend refinishing floors. Instead replacing or regrouting are better options.
Lastly, changing out vanities, toilets, medicine cabinets, towel bars, faucets, handles and all the smaller items can have a dramatic effect. As long as you are not moving around plumbing and buying really expensive stuff you should be able to save.
Oh ya, one more thing instead of ripping out buckling, peeling, cracking or uneven walls why not skim coat the walls.
Anyway, let me know what you think. Do you have any ideas to save money on bathroom remodeling?