I didn't do much research on pricing so ended up paying about $100. The 'Boxster S' part can say a number of different things. You can also do two lines, like Porsche, then Boxter under that. You can get them at Suncoast, see link below.
They actually attach in a totally different way. You get these clips, and one side of the clip is installed right into the rail the seat is on (you have to remove this plastic cover then hook it in there). Then the other side of the clip is attached to the underside of the matt and the two parts clip together. Works really well, very secure.
http://e-partssales.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=P&Product_Code=lloydmats987&Category_Code=987int