I agree that if you don't mind the driver being all new and shiny then going to somewhere like AG may throw up a bargain or two. Without knowing your budget it is hard to make suggestions but I reckon that there must be some Ping G5's knocking around now the G10 has been out a while. I know my local AG is doing NEW Callaway Big Bertha 460 for around the Ł120-130 mark which I can't imagine being vastly over budget.

If you go to AG at least you can have a go on the launch monitor which will give you a rough idea how well you are hitting x brand even if you can't actually see the shot. Make use of the bigger retailers for testing and then perhaps use the Direct Golf as mentioned and see if the price is right