It's made by Delta, Ray and I picked it up at a woodworking show. I have Delta's 16 1/2" drill press and it attaches to the quill in just a few minutes. It also comes with a bushing or adapter for attaching to a different quill size. I think the sizes are fairly standard between the two so I think it will attach to most drill presses. I only paid $60 something for it if I remember right. It comes with 4 sizes of chisels, 1/4, 5/16, 3/8, and 1/2. There is a little trick to setting the bit inside the chisel properly but it's not hard, you just have to pay attention.
You can buy a dedicated mortiser but it takes up a lot of bench space and they cost around $450-500. For a few dollars more you can buy a floor model drill press and the mortising attachment and you'll have a drill press when you aren't using the attachment. The dedicated mortiser will usually also do 5/8 but the attachment will do any size by working both sides of larger mortises.
Lee Valley sells some cone shaped sharpening stones for the chisels and I highly recommend them. I had to sharpen one chisel a while back and just spun the stone in my fingers for a minute maybe and the next cut was like slicing through warm butter.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.