If you go for an N810, I think $260 is too much these days; you can probably get one for around $220, as buy.com has had them for $210 shipped twice now. (I think buy.com has them higher now, but there's other places, and barely used ones that were bought for $210 being resold...)

Better ones (next-generation processor, high-def (probably 5MP) camera, HSPA data) will be coming out this year, but maybe not before June, and definitely priced over $300. So while you might still feel remorse, it honestly won't meet the conditions you've stated. (It might be worth the extra cash and wait, or might not.)

For info on the features we can expect in the next model, see this thread; I think prevailing guesswork puts release in the late second to early third quarter, and price $500 to $550, but that's all speculative. IIRC, Nokia did indicate it would be out in the first half of 2009, but somehow deadlines always slide...

And with the addition of HSPA data, there's always the question of frequencies. You will still be able to use it with no cellular data, though, and I think it'll be worth it even without that.