Where to find an accurate Mercator Projection world image? I'm sorry if this doesn't fit "Earth Science" too well. No idea where else to ask this!

Can anyone help me find an accurate world map in Mercator Projection?
It doesn't need political borders or too much detail, just coastlines would do.
(Ideally with land coloured buff and sea coloured blue, but I'm not picky!)
I would be happy to pay, if it isn't too much - unless there are free resources out there!

I'm writing a modelling application where I need to plot Lat and Lon on a world chart so it needs to be fairly accurate (if you call Mercator Projection accurate).

Thanks for any help, and sorry if I've broken any rules here.
So here is the way I do that personnally with NaturalEarth data and R (but you can do something similar i m assuming with any programming language that can deal with GIS or any GIS software):

Fist download and unzip the file:



download.file("http://www.naturalearthdata.com/http//www.naturalearthdata.com/download/10m/physical/ne_10m_coastline.zip", "10m_coast.zip")
unzip("10m_coast.zip")


Then reads in the shapefile:

library(rgdal)
library(maptools)
a &lt;- readShapeSpatial("ne_10m_coastline.shp",CRS("+proj=latlon +ellps=GRS80"))


Then project it:

a_merc &lt;- spTransform(a,CRS("+proj=merc +ellps=GRS80"))


And plot it:

pdf(w=20,h=20,file="merc.pdf")
par(mar=c(0,0,0,0))
plot(a_merc,asp=1,xaxs="i",yaxs="i")
dev.off()


This is a very minimalist example of course, it only draws the coastlines (as a line by opposition to drawing the continents as polygons, that would allow a more advanced colouring scheme but the projection to mercator of polygons is more complex, as Antarctica creates problems).