Keeping the Same Layout Can Save
You may not like that your bathroom - maybe you think it is too small. The cost of updating a bathroom can be in the $10,000 range. But if you are moving walls, water lines, the bathtub, etc. to accommodate a larger layout, then you'll really be reaching into your bank account with additional costs for a plumber, electrician, etc.
Do Some Work Yourself
Save some money if you are handy. Or maybe you have a handy relative or friend that can help. Watch online tutorials if you're not sure how to do something. Maybe only part of the job is up to your speed. A plumber can attach the sink, toilet and bathtub, but you lay the tile. Whatever it is, a few dollars saved over here and there add up.
Find Inexpensive Accessories
Good sources can be garage sales or Craig's List, Next Door, Facebook. You never know when you find that particular treasure. Keep an open mind too. Think creatively outside the box. An old dresser made of what is now stressed wood could make a good bathroom vanity. Not only would something like that bring character to your bathroom, but it will have your guests talking.
Before you toss the old cabinets or bathtub into the dumpster, think about resurfacing. Sometimes that's all you may need to bring back the look of "new" and you will have saved yourself some money in the process.
Look for Remnants
Quite often, stone yards, contractors, tile shops, etc. have leftovers from previous jobs or from cut slabs. You may be able to purchase these at a discount. After all, it's often useless to the owner - but can be valuable to you if you only need small amounts.