You can probably find a Dancer with skirt for $50 if you look around, though they're starting to disappear from the market as more of them succumb to age/brittleness. With a tiny (by modern standards) cockpit and narrow, rounded hull, a Dancer is probably the closest approximation to a sea kayak - very log-like and easy to roll. Certainly the few sea kayaks I've been in rolled a lot like a Dancer.
If you want easy, the RPM is probably the easiest rolling boat ever made, but that's not necessarily a good thing. It'll let you come up with some seriously flawed technique, especially in the calm of a pool. That can translate to a very unreliable roll in conditions or if you get in a less forgiving boat.
Heel and Pegpads™
Touring Kayak Paddles
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