Need more information.
What voltages and currents do you need?
Anyway if you are spending $500, I would seriously consider getting two power supplies.
Definitely want at least a dual output power supplies with supplies that either can be used as separate isolated supplies or tracking +/- supplies. For a second supply, you could probably get away with a smaller single output supply, but it is really handy to have that extra independent supply available.
The new ones with the digital displays, power meters, etc are pretty nice, but older style supplies do the same job. The older transformer based supplies with linear regulators will be heavier and perhaps lower current, but will almost certainly have less output noise. If you are working in audio, it may be a factor.
You may be able to get a couple of excellent second hand HP supplies, and have change left over. The older HP supplies use common parts and the manuals are easily available, so repairs are easy - particularly with no digital circuitry.
If space is limited, or you need a high current supply in a small space, then you will be looking at something new.
Richard.