No one can begin to answer your question as you have provided virtually no details about what the present situation is, what would need to be done with cabinets, what the plumbing access would be, etc. It could be anywhere from $1000 to $10,000, and would vary greatly based on geograhic location. I suggest you get several local contractors to give you estimates, if you want something that is reasonably accurate.

First of all, are you on a slab or is there a crawlspace? Getting three or more competitive bids, though, will still be needed to get a budget figure. Make sure they are all bidding on the same specified end product.

Existing plumbing is probably in the wall under the sink, and it connects to a drain in the floor and has a vent running to the roof. If you move the sink you will have to reroute this drain and vent. If you have the wall completely opened up, you will have "access" to make some changes, but it may be difficult to work around obstructions in the wall. If you are also changing cabinets, you have to consider the path of the vent and drain and how it would fit with the drawers, etc. It is not a simple question.

Bruce

Access means how easy it is to access the existing plumbing so you can run it to a new location. If you are on a slab, it's more complicated as you can't get under the floor to run the plumbing easily to the new location. If it comes down from an accessible attic, it might be easy to extend it to the new location and drop it down from the attic. If it comes up from the slab, you would have to run it sideways through the wall(s), or up to the attic and back down again. In addition, you have to be able to tie in to the sewer and vent pipes, and there are code requirements regarding horizontal distances. I know you thought you asked a simple question, but you didn't...and your specific layout will have a huge impact on costs. That's why you need a contractor to look at and assess how simple or complex this will be. It may be easy, it may be difficult (involving jackhammering the floor, etc.), Oor it may be next to impossible unless you spend a lot of money.