If I had $1500 to spend and wanted to take pictures of geckos as well as general pics (family gatherings, walks inthe park, at the zoo, etc), this is what I would do (keep in mind I'm a Nikon guy).
Nikon D50 (body only) $500
Tamron 90mm macro $450
Tamron 28-300mm $400
Sigma EM-140 DG ring flash $360
It's a little bit over your $1500 limit, but well worth it. With the 90mm and the ring flash, you can take endless varieties of close ups and portrait-type shots. The lens rules for anything within about 10 feet of you, it's tack sharp, and is very easy to get good shots with. The ring flash works great and is far less expensive than competing rings of similar quality. The 28-300 is a perfect general purpose "walking around" lens. You can do everything from wide open landscape shots to tight candid face shots from a distance. It's the lens I keep on my camera unless I have a particular need for another type of lens.
The one thing you're not taking into account here is the $500 or so you will need to spend on an extra battery and a bigger flash card. The extra battery is needed so that you can keep one on the charger and one in the camera all the time, that way you're never stuck with a dead battery. When you know you're going to spend a day out shooting, swap the battery and you're good to go. You don't need an 8 gig flash card, but I would get at least a 1 gig. I currently use a 2 gig card, and with the camera set to the highest quality jpeg mode, I can take about 580 pictures on that card, and I've never filled it up like that. Bigger cards will only really be useful if you are shooting in raw mode, because then you only get like 130 pics on a 2 gig card, which is still a lot, but not enough for a full day out shooting.
With those, you can do pretty much anything you want without being constrained by your equipment, which will allow you to save up for the expensive lenses you really want but take time to afford. Honestly, you're not going to get your money's worth out of a newer model or higher end camera body. The only way you would know what you want from the higher end and newer model bodies would be if you already had an SLR and you had decided that it wasn't doing the job. Since that's not the case, don't waste money on a bunch of features you'll probably never use. The D50 does everything you need. Lenses are where you should put your money, you can always upgrade the body later if you find it doesn't do everything you want.
It's like when a kid wants to learn to play guitar, and they see a $4k Les Paul in the store and want it. If you ask them why, they can't tell you, they just know it's cool. But they won't learn any better on the $4k Les Paul than they will on a $99 Squier Bullet Strat, and once they learn how to play they may not even like Les Pauls, so why spend that kind of money on it right off the bat when you don't even know if you want the features it has?
Buy the camera body by itself, don't get the kit lens because they are usually not great and they can double the cost of the camera. Buy exactly the lenses you want and need, and that way, once you have $3k-$4k of lenses, it won't seem like a big deal to upgrade from a $500 body to a $1000 body, because the expensive part (the lenses) works for both of them.
ryanm
