rstopher's suggestion to get a triple supply is spot on. As is the usefulness of having a dual +- setting thats higher and a single supply that can do lower voltages at a higher current.
Fully floating (dual or more) multiple power supplies can - if you need to do this, be used in series or parallel to give you more voltage or more current.
Really good multiple ones will also have means of using them both at the same time as a dual positive and negative supply with a center ground. Good for precision op amps.
I actually have two triple supplies now.
One is digital one is analog.
For most of what I do, I really like having the precise digital readout for low voltages and especially the current limit. (which makes a small click when it starts limiting- also an LED changes color) It is a Sorensen "XL" series triple supply that can provide 60 watts (conservatively rated) in each section.
What I do is I look up, what is the current draw supposed to be?
Then I set the supply for exactly that plus around 20%. Sometimes when you have wired up a circuit you have made some simple - but sometimes not so obvious mistake. Without a current limit, or if it is set to high, your part may instantly become toast if you hook it up wrong.
If you limit the current you vastly reduce (if not eliminate) the chance of causing any damage to your components under the usual kinds of error conditions. The more precise you can set the limit to the better. Supplies vary in terms of their accuracy and ease of use there.
It helps that most of the things I work on take very little current - but its probably prevented problems many times.
You can get help and advice here, use it to get a deal on a better than average supply. I would look for a quality lab supply thats being sold by a reputable dealer that has some fixable issue. You'll likely save a lot. Older supplies rarely have parts in them you can't buy yourself. There also you can get advice here. When you see a unit being sold on ebay, look for its service manual and download and read it.
Yes, older supplies are a gamble and often they are less convenient to use - for example, mine weighs a lot, hums noticeably when its on, (but doesn't need a fan) and because of its weight, is kind of a pain to move between my two temporary work bench areas.. but that fine-grained dial in is really nice to have. And its so accurate I never need to check it.
I have and as far as I can tell, its still within spec, its accurate to four digits.
A power supply is the one thing you use pretty much all of the time.