r/Hipstamatic

Hey everyone, I began using Hipstamatic back in around 2010 when I had an iPhone 3GS, and then used it again when I upgraded to an iPhone 4S. Later I switched to Android and haven't been back. Recently I was thinking about the old Hipstamatic app, and I learned that it's still available. I loved the app so much that I'd like to get a newer used iPhone to use with the old Hipstamatic app. I'm not looking to replace my main Android phone, and this iPhone would become a dedicated Hipstamatic camera that I'd use for this and really nothing else. I'd also like to pay about $150 (or less!) for the phone off of eBay or some other site if possible. Any suggestions on what iPhone models I should consider?