Bird photography on the cheap (?cheep)

Last summer I moved to Palo Alto, where I live in the middle of the urban sprawl that runs from San Francisco down to San Jose. One urgent need was to find a good place to go for walks, away from the traffic and the concrete, even if it meant a short drive. The answer was to return to an old favourite location: the Baylands Nature Preserve and the many trails that wind around Charleston Slough at the edges of San Francisco Bay. Charleston Slough“Old favourite”, because during my many years at Sun Microsystems, I would often visit the SunLabs building (MTV29), and the parking lot behind the building backed right on to Shoreline Lake. On many occasions I would wrap up a day’s work in MTV29 and then go for a walk around the Slough (often before heading up to SFO to catch the red-eye home to BOS.)
Which brings me to birds, and photography. The wetlands around Charleston Slough are a mecca for birdwatching. Egrets, pelicans, ducks of many different kinds and colours, waders, insect-eaters… every visit brings something new. New, interesting, and usually several hundred feet away! (Though there are some incredibly tame fearless egrets at Shoreline Lake.) And frankly my current camera – the Panasonic Lumix DMC-TZ4 – doesn’t really hack it. The 10x zoom is fine for day-to-day stuff, but it’s not going to let me distinguish between the various kinds of ducks or waders out in the wetlands.
The obvious answer would be to grit my teeth and spend the money to get a DSLR with a couple of decent lenses. Obvious, but expensive: at least a kilobuck, all in. And I’m intrigued by the recent emergence of ultrazoom point-and-shoots. Things like the Olympus SP-590UZ (26x), the Nikon Coolpix P90 (24x), or the forthcoming Fujifilm FinePix HS10 (30x!). All of these look like much more affordable (and less fiddly) solutions to the problem.
Recommendations, anyone?