if there is enough room for a waste basket under the counters, then there is enough room to do this with the cabinet front, rather than the counter TOP you will create more "demand" for your services by modifying the cabinet front to include the waste receptacle "hole" and installing a waste can on a sliding mechanism. -just a thought...
all in all, like anything else, this all depends on what your customer is willing to spend, what you need to make and several other factors... if they are in a paradigm whereas they are assuming someone can walk through with a magic wand and "will" cleanly cut, finished 8" diameter holes in the corian... you'll need to explain reality to them. -I doubt they are intending to spend $1500-$2000 on 6 holes being cut in the bathroom counter tops... am I right? so buying a new OF2200 for this might be pushing it a bit, unless you really REALY want to buy one and are thinking of this as a financial assist...
can you cut a perfect circle with the tools you own?
I would start with a template. MDF will be fine, since you only need to cut 6 finished holes, Veneer core plywood is OK, but I would use MDF or PVC for this.
cut a 8" hole in the center of a 20-24" square drop of your material of choice. dress any anomalies with bondo, and fair out, so you have a good template to work from,, then using a pattern bit, cut a 2nd template, and KEEP the original, incase you damage the working template...
mark out all your holes, and cutout the waste first, leaving only about 1/8" from the line, then cut the rest out with a router
a solid surface specific bit is what you'll need, and a PATTERN bit, or a "Top Bearing Copy Bit" is what you're going to use for this exercise.
WEAR A RESPIRATOR! the dust that comes off that stuff is pretty nasty!
but... if you can convince them to do this without cutting the surface, you can likely make more work for yourself, provide a better solution, and everyone will be happier.
Modify cabinet front......
fabricate and install waste receptacle
http://www.google.com/products/catalog?q=under+counter+waste+can&um=1&ie=UTF-8&tbm=shop&cid=3063091826945805181&sa=X&ei=c0j_TpmkHI-5twfy16n1Cg&ved=0CI8BEPMCMAE