I don't think you're going to find any plastic kits that represent that sort of vessel. It's not really suited to the plastic kit medium.
The only pram kit of which I'm aware is the one offered by Wooden Boat magazine, through its "WoodenBoat Store." It's called the "Nutshell Pram." The same firm offers plans and and kit to build the full-size (7-foot) boat. The kit is intended as a sort of dress rehearsal for people who intend to build and sail/row the real thing. But the model is a pretty one in its own right. Here's the link: http://www.woodenboatstore.com/prodinfo.asp?number=620-001 .
Be warned: WoodenBoat invariably sells high-quality merchandise, but to call this thing a "kit" stretches the dictionary meaning of the term to its limit. A member of our model club brought one to the last meeting. What's in the box is a nicely-drawn set of plans, a well-written set of instructions, and some wood. None of the parts is pre-fabricated in any way. It's really an exercise in scratchbuilding - and a great way to break into that form of modeling.
That same firm offers several other small boat kits. It's worth browsing the site.
Wooden Boat also publishes a volume called The Expectant Father's Cradle Boat Book. It describes how to build your choice of two designs for a baby cradle shaped like a boat. Stretching the parameters of the title just a bit, I used the plans to build a "cradle pram" for my first grandchild. It came out great (I think), and has since been passed down to the little sister of the individual in question. Our intention is that it will become a family heirloom.
Another manufacturer worth checking out is Bluejacket ( www.bluejacketinc.com ). The Bluejacket line doesn't include a pram, but it does have a number of other interesting small boat types - most notably a couple of dories, several sailing yachts, a Muscongus Bay lobster smack, and a Penobscot Bay salmon boat.
The line of kits offered by a firm called Midwest also includes several small working sailboat types. I don't have a website for Midwest, but I think ModelExpo ( www.modelexpoonline.com ) carries at least some of the firm's products.
All these make great projects for newcomers to the hobby. Too many "newbies" insist on starting with a Victory, Constitution, or Cutty Sark. The vast majority of such models never get finished. The truth is that there's an immense amount of pleasure, satisfaction, and information to be gleaned from building a model of a small boat. And any sailor knows that a Grand Banks dory or a New Bedford whaleboat is, in its own way, a thing of great and subtle beauty. I'd be delighted to have a nice model of any of the aforementioned boat types in my house.
Good luck. It's a great hobby.