Detox Question

I got a drug test monday, specifically a piss test. My main problem is the nearest headshop is over an hour away and i have an old car that might not make it, so I've looked for cleansers at stores like GNC,etc. Most of the stores didnt have much, liver and colon cleansers were plenty, but otherwise it wasnt. I came upon this place called "Vitamin Shoppe" and it has a detox called special urinary cleanser. It says it cleanses your urinary tract, bladder, and...well i forget the third thing. I was just wondering to anyone who knows a lot about this: will this product work? i dotn know anything about how much stays in your system or what actually needs to be cleansed so i didnt wanna buy it and have it not work. Im prepared to drive to the headshop if need be but i'd rather not chance it, any help or any specific products that you would recommend would be appreciated, im looking for names in particular cuz ive never had to do this so i dont know which products work and im trying only to spend 20-30 bucks if possible, i usually smoke sometimes everyday or every other day and the last time ive smoked was earlier today (just found out about the test now) if that factors into anything.