Trouble With Radio Shack, "You've Got Questions but they DON'T have
answers".  Never rely on a Radio Shack clerk to tell you what they
stock.  There is a one foot cable 42-2497 for about $4.  If you really
want the 90 degrees bad, you could spend another $4 for 274-372.  The
way to check radio Shack is at radioshack.com.  Don't use the search
because they only use "OR" searching.  For example, if you put in
"adapter cables"  they'd give you everything that matched "adapter"
plus everything that matched "cables".  Use the category list.  You
can then choose a sub-category and a sub-sub category, etc.  You'll
usually have to click on an item to find out enough to know what it
is.

you could always solder together one.  It woudln't be difficult and you
could get exactly what you want.  Of course, you need to know how to solder.

-Bruce