DSLRs are stupid cheep, dude. I paid $1800 for a used Nikon F5 in 2002. Y'all get off so easy these days. Look at it this way: a camera is nothing more than a box with a hole in it. You can control how long that hole stays open, how big it is, and what's in front of it. That's it. When you aren't using an SLR, you're giving up control over the first two of those three parameters. Your P510 gives you a lot more control than an iPhone but whenever I see "43x zoom" I know I'm looking at shitty glass. Nice thing about an SLR? You can trade in your shitty glass. Tell you what: buy this book. Look it over and see how many of the techniques within it can be accomplished with your P510. Do those. Then when you've beaten your camera into the ground, get a better one. I shot a Nikon N70 for two years until the shit it couldn't do was boning me. Then I moved up to the F5 until I found its limits. Then I shot a Pentax 6x7 until the whole fucking world forgot how to develop slide film and I had to stop taking pictures for like five years. Then I bought a Canon 5D for craptacular amounts of money and it's been serving me well for like 10 years 'cuz I got good glass. Eventually I'll upgrade to something better but "something better" is now like $10k rather than $2k so I'm not in a hurry. If what you got isn't holding you back yet, there's no reason to upgrade. There is, however, ample reason to push past your limits.
The worst thing about the early DSLRs was they were all APS sensors. I had the D70 for the longest time because I refused to "upgrade" to another APS sensor body, and I had invested stupid amounts of money in nikkor lenses (most of which were full frame). They then released the D600 a couple of years ago which was still expensive, but for a full frame camera, $2000 was cheap ... if I ever find the limits of that camera, I'll be super suprised. Once you're paying decent money for camera gear, the lenses become more important. My favourites are my 50mm 1:1.8, a 24mm 1:1.4 and my 80-200mm f.28, all nikkor. That 24mm is ridiculous in low light.
Yeah, I went Canon for the simple fact that Canon had released three full-frame DSLRs while Nikon had yet to release a single one. Now? now I'm thinking of going Nikon again. I would argue that the worst thing about the early DSLRs were that they were crazy f'n expensive. Pepperidge Farm remembers.
In 1995, the DCS 460 was the highest resolution digital camera available and its list price was US$ 35,600. When it closed out in November 2000, the price had dropped to US$ 2,500.
Hahaha yeah I didn't get into it quite that early: Was a good camera but the battery life was awful. And the body had standard camera batteries for the "camera" part, provided by Nikon, while the digital sensor and other electronics were powered by rechargeable AA's.