Well, for example, if you got the SX30 IS, you can get a
Lensmate 58mm Thread Filter Adapter for $20, and then some
excellent filters in the $25-$50 range. Pay close attention to the Moose filter. Awesome for wildlife photography, it's a combination of a warming and a polarizing filter.
If you really want an digital SLR, then an EOS Rebel is hard to beat. And there's tons of lens options for it. But for what you want to do, all things considered (especially the "lost" part), then the SX30 IS would be my recommendation.
The best point-n-shoot is probably the Canon S95, and the best budget dSLR is probably the Canon T2i, and the SX30 IS is right in between, with all the manual controls available with the T2i with the ease of use of the S95. The SX30 can be used in fully automatic point-n-shoot mode, or fully manual where you control everything, and anywhere in between. And it does it with a single lens that does both wide angle and a 35x zoom without distortion or aberration. It all depends on whether you really want and/or need that SLR.