You would be better off spending the money on a less expensive serger than paying extra for this foot. You probably will not be happy with it's proformance.
Some of the manufacturers claim that a overcast stitch that is built into the machine is a serging stitch. You have to have the fabric lined up just right to catch the edge.
I personally don't care for it.

Thank you all for your replies. It sounds like I'm better off just getting a serger.

I have the "serger attachment" for Singer, but contrary to Singer's claims on HSN, the darn thing most certainly does not turn your sewing machine into a serger. :lol:

I don't know how they can even say that with a straight face! But, I didn't know much about machines at the time - I didn't have a serger and didn't think I needed one - and I fell for the advertising.