You can still order them online from Best Buy for the 199.99 price (3G/Wifi) or 189.99 (Wifi only).
But otherwise, yeah, most places aren't selling them anymore in major stores due to the release of the Slim.
You can sometimes find them in lesser known stores. My K-Mart of all places had a PS Vita Madden 13 bundle lol, and that was only a week ago. I was thinking of getting it, but I then looked closer and I could see it was an open item return and it was still 199.99 so I just ordered online from Best Buy.
Dizzy, you dont want a used Vita. Or any handheld for that matter. My first Vita was a gamestop refurbished. Dont waste your time bro. Either wait for the Slim model releasing next month, or buy the OLED brand new, straight from Sony. Its brand new, free shipping, and worth the asking price: http://store.sony.com/playstation-vita-wi-fi-and-3g--zid27-PSV22032/cat-27-catid-All-PlayStation-Vita?_t=pfm%3Dcategory