I doubt it fits into your inexpensive category, but I would recommend looking into the Folbot Greenland 2. I have heard a lot of great things about it.
Another alternative, and its not necessarily cheaper than buying an already made one and it will mean giving up a few weekends of precious fishing, but you could build your own, which allows you the option of building into it what you would like in the perfect FF kayak. I have some plans on a Yahoo group that I am the owner of. I don't believe any are for tandems, but that can be remedied by increasing the distance between forms to lengthen the boat and also increasing the cockpits. Of all the plans on that group (and there aren't many) probably the only one worth attempting would be the King Canvasback, which is a skin on frame kayak. People have fished out of SOF kayaks for centuries, so don't listen to anyone saying "don't do it", just know that there is always the risk of puncturing the hull with the hook, but any hole should be small enough not to cause too much worry (yes, I would still get to the nearest shore to check things out if that were to happen)and the skin can be easily patched. (Note: the plans are in the Files section, also you'll have to "join" but acceptance is automatic)
[url=http://groups.yahoo.com/group/kayakcanoeplans/:28d9b]http://groups.yahoo.com/group/kayakcanoeplans/[/url:28d9b]
Also a company that I bought kayak plans from and that has turned into one of my current projects is Clark Craft. The website is [url=http://www.clarkcraft.com,:28d9b]www.clarkcraft.com,[/url:28d9b] I believe.
None of these plans that I mention are state of the art in kayak building, but CC and the King Canvasback are wider than the modern plans and should be pretty stable for fishing from.
If you (or anyone following this thread) are interested in this approach, contact me via email (through the Yahoo group above) and I can provide a couple of very informative links and also provide answers to some questions (I'm not all that knowledgeable myself, so I may have to direct you someplace else for the answer) and some of my opinions/suggestions if you choose to build the King Canvasback (like not using 3/4" plywood for the frames, per the plans, due to that being a big cause in making the kayak very heavy, 1/2" should be sufficient based on the CC kayak I am building of a similar design, but the design calls for using 3/8" plywood, I am using 1/2" since I didn't buy Marine Grade plywood, etc.).
Paul