You may want to check out Lloyd Rubbertite Cargo mat. Have a full set (Front, rear and cargo) in my wife's 08 RX350 and the fit/finish are just about perfect and they are heavy with spike so they stay in place. Best part is the Ivory color mats matches with the factory Tan interior quite well.
Although a whole set were quite pricey at ~$200 shipped.
08 RX350 AWD (wife)
08 Avalon Touring (mine)