Best Eyepiece for 5" Scope to View Saturn

Looking in the Orion catalog I can spend anywhere from $25 to $700 on
an eyepiece. I'd like to spend about $75, but only if I can get
something that will work reasonably well to view Saturn. I suppose I
want the most magnification I can for my 5" reflection scope.

Right now I have what came with my Celestron: a crappy 3x Barlow, a
4cm and a usable 20cm.

Can anyone help me figure out what's the best thing to get? I'm
thinking of replacing the Barlow eventually with a Tri-Mex 3x, but
first I want to focus (ha ha) on the eyepiece.

~ L