There are many varieties of bathroom vanities available in the market. A typically mass-produced bathroom vanity commonly found in most home improvement and hardware stores can cost around $40 to $150 for a basic single-sink model. Average vanity price normally starts at $200 and goes way up to $800. Succeeding sizes can cost a homeowner around $3,875 to $18,850 and may still vary depending on the style and materials used or the number of sinks included. One things that also define the price of a vanity is on whether it comes with a countertop and sink or not. On the other hand, semi-custom to custom made bathroom vanities from showrooms or cabinet makers can cost a homeowner around $75 to $250 a square foot. In addition to the cost, a contractor can charge $100 to $300 for installing Castro Valley bathroom vanities.