There's a little more to impedance than just the manufacturer-supplied value. Two IEMs can be listed at 16 ohms, but one might have a flat impedance curve that has no (or minimal) impedance interactions with sources, whereas the other might have a roller coaster of a curve that results in very odd behavior with some sources.
Anyway, I've got to be honest, $35-50 is not a huge budget for a long-term IEM investment that's also an upgrade to one of the best budget earphones around.
Out of the ones you are looking at the Ety Kids might be the best option if you don't mind being "volume limited" on your portable sources
by the high impedance. Otherwise I'd go E30 or VC02 for slightly different sound sigs. The E30 isn't necessarily an upgrade to an 8320 in sound, but it is a much more ergonomic earphone. The VC02, as others have said, has touchy connectors.
My real recommendation would actually be to consider the Ostry KC06 instead. Just saw it at
mp4nation for $50 after coupon this morning . It's a very sensitive earphone but I still think its performance is a better fit for what you want than the others you're considering. You just might hear a little hiss with those sources of yours that are not optimized for earphones (but definitely will be fine with the Clip+).
Hidition NT6 (http://theheadphonelist.com/headphone_review/hidition-nt-6/) and Custom Art Harmony 8 Pro (http://theheadphonelist.com/brief-impressions-custom-art-harmony-8-pro-pro-330-v2/)