If you absolutely can't get both, I'd say get the random-orbit and use
a hand sanding bolck to get into corners.

I agree also. I've been very happy with my $35 Ryobi RO sander, but I
haven't used the big names, so I can't comment on those.
As far as paper, if you must buy from Home Depot, I'd definitely look
at Norton 3X sandpaper discs. They might not have it on their website,
but I think they almost certainly would in the store. Even better than
that, I'd recommend Mirka Gold discs from Amazon (do a search depending
on the size and number of holes you need). Lee Valley is a top-notch
company to deal with, and they also have several types of sanding
discs, such as
http://www.leevalley.com/wood/page.a...10&cat=1,42500 if you
need 5" discs. I'd recommend looking for something that says no-load
or reduced loading - finish, glue, etc would gunk up regular sandpaper
pretty quickly, and low-loading paper would reduce this somewhat.
Finally, I'd recommend hooking whatever sander you get up to a vacuum,
even if it comes with a little dust collection bag. The vac will keep
your air cleaner, but will also extend the life of your sandpaper as
less gunk will have a chance to build up. Of course you'll need discs
with holes to match your sander for this to work (standards are either
5- or 8-hole).
Hope this helps,
Andy