The amount is not prescribed the statue just requires that is is a thing of value so techically it can be one dollar, or even a goat, but realistically @Jeff Copeland is correct. 

The vanities were in bad shape, so we have already bought some upgraded vanities with real marble* tops and new faucets, but not sure if we should also do a major remodel to replace the dated 1980's floor and wall tile, "Roman" whirlpool tub ("bone" colored), "bone" colored toilet, and acrylic shower stall.

Looking at our budget, we having to consider updating both bathrooms some but leaving things like the florescent light boxes above the vanities in and the cultured marble (aka fake cheap marble), or we can fully update the master bath and just do some small things like paint the guest bath.  

My designer has porcelain tiles that look like hardwood and a buddy has porcelain that looks like marble but much more durable and easy to clean (and cheaper).

Then you can place marble-sized balls in areas in wet or damp areas, like under sinks, near water heater, etc.

I can do a small bathroom with a nice all wood vanity with granite or marble top for $1500 to $2000.. $7k or more for a bathroom remodel of a small bathroom is a ripoff..$5k for 3 days of work for 1 person?

I'm not sure of the statue of limitations on this, but chances are high that you'll be on the hook for these repairs.

Will it sell without marble counters or is that a huge waste of money?

@Ted Lanzaro  not to debate this at all ... and to have a friendly debate on the subject.Being a CPA you have far more knowledge then the average person and ability to look up state statues and understand them.Have you ever looked up your states real estate sales code..

typically 2 to 3 years and very common for them to file charges he last week before statue of limitations has run..