This is the closest smog spot for me- exterior isn't anything fancy, and no one was here when I walked up. Check in the adjacent gas station convenience store and someone will be right out...
There are posted notices about a discount for using cash, but no posted prices? The employee who helped me was friendly, but a bit odd. He rather discretely whispered to me that he was going to charge me $20- which was the regular price printed on the form, so I'm not sure what the deal was there.
Not the best area. A homeless guy was standing around telling me I was pretty and making me extremely uncomfortable before the Smog guy shooed him off. Over and done with in under 5 minutes though, and he gave me some helpful tips about registering my car.