My Koss cans are falling apart. Any thoughts on some cheap headphones? I mean $30 or less. I only use for tracking vox, I do not mix with them.

I'm not sure you can find good "studio headphones" in that price range, but Koss Porta Pros should last and work well if you take care of them. They're great for long sessions.
 
https://www.amazon.com/Koss-PortaPro-Headphones-with-Case/dp/B00001P4ZH
 
The only other decent cans I can think of in that price range would be the Sennheiser HD202 II.
 
https://www.amazon.com/Sennheiser-202-Professional-Headphones-Black/dp/B003LPTAYI
 
EDIT: I'll also mention I've seen the Grado Prestige Series SR60e on sale for $60 a few times this year. They're not very comfortable for extended use, but they're built well and sound good.

The koss look like they could have sound bleed? Do they cup over the ear like the Sennheiser's? Or have an option?

+1 for the Sennheiser HD 202
 
My first pair of headphones were the closed back Sennheiser HD 202.  I must say I really loved those headphones when I first started and now I keep two pair in my studio as backup cans.   Make sure you get closed back headphones.
 
I moved on to the Audio-Technica ATH-M40's and M50's.

koikane
The koss look like they could have sound bleed? Do they cup over the ear like the Sennheiser's? Or have an option?

No, they are very open.

Here is another option,  The AKG K52 over-ear, closed-back headphones
 
$29 at Guitar Center on Sale now!
http://www.guitarcenter.c...hones-1444141025115.gc
 
 
$49 at Musicians Friend
http://www.musiciansfriend.com/pro-audio/akg-k52-headphones?rNtt=AKG%20K52%20Headphones&index=1
 
 
 
 

Marantz MPH-2 Professional Studio Headphones - $40
 
http://www.guitarcenter.com/Marantz/MPH-2-Professional-Studio-Headphones.gc
 

Because headphones are now a huge consumer market there is now the mass production of all types.  
With this comes both the overpriced junk and some great deals on some very usable phones. I believe they are all manufactured about the same way and the price is more a marketing strategy. And I think some old trusted name brands are also now sourcing from the same factories in China. Those factories specialise in customising orders over 1,000 and just put different labels or the shape of a little piece of plastic to suit. 
 
I cruise the dollar stores which are the dumping grounds for no name stuff. Just look at the way they are built, then I take a chance for $10-$16 and buy a set. Out of these I have found a few that are on par with my $100+ collection of name brand phones. Some have seen a lot of use for over 3 years now. 
I go back and buy a bunch once tested. I now have a dozen or so for when I need them. All for the price of 1 set of name brand.