Bullnosing with tile

Greetings,

I'm building a mantle for a gas fireplace and I have some questions about making an attractive edge around the bench.  A couple of places sell pre-made edge pieces.  For my 30sq foot installation I'd pay $600 from one site or $700 from Bedrock Creations,.  (I looked into slabs, but they are too pricey.  However if you are in the Seattle area I strongly recommend a trip to Michaelangelo's granite and marble warehouse.  It's a fabulous dream world of stone.)

My other option is to pay $300 for 60 tiles  that a neighbor is selling.   I suppose I could make a square lip by arranging strips of tile at right angles, or I could laminate three layers along the outside edge and then polish this to the slightly rounded square look.  To do this I'd buy a set of 4" stone polishing disks for  $80 or so.

Here are my questions.  First, is the Omnigrip pre-mixed mastic safe for granite?  The cannister says so, but I've seen reports of granite discoloration from pre-mixed products.

Second, is my laminated edge a good idea?  Obviously it will show seams, but is there anything else I should consider?  What's a good glue to laminate granite tile?

Finally, any recommendation about spending the extra money for pre-made edging versus making my own?

Thanks in advance.