At the very least, a nice side-expansion port RAM unit can sometimes be picked up cheaply (<$50) and makes doing things like transferring ADFs over to the Amiga with a term program and writing floppies from them possible. Of course, many hard drive units may come with some additional memory for the system installed, but if you're on a budget a simple RAM expansion can give you some room to work.
The 500+ is also nice because you can add a full 1mb to the trapdoor for 2MB of chipram. Mine came with a 512kb upgrade which I swapped out for a 1MB unit when I found one cheap enough.
