Depends what you mean by smart. I've got a pair of 3.5" android handsets by (LG?) - one I got for $20 and includes FreedomPop service for free, and one is a $10 Tracfone branded of essentially the same type. I've used them as temporary phones for family on vacation where we knew we'd be separated. Kept in touch via voice/text/hangouts, played music, took pictures, checked email, looked up times/maps on the internet.
It's every bit a smart phone, for $20.