You can get the Hifimediy Sabre Tiny USB DAC for $30
While you can plug in your iem directly, it is supposed to be used with an amp, you could get something decent and cheap such as a Fiio E6 which can be found for under $30, so hopefully you can get both items within your $60 budget.
There are a few reviews around for this DAC, you can also check the UD100 thread which is basically the same product to see how it performs.
Note: Hifimediy Sabre Tiny USB DAC and UD100 both use Sabre ES9023 DAC + PCM2706 USB receiver, the UD110 also mentioned in the thread above has different spec and components, just making sure you do not get mixed up with the different products.
EDIT: I had a look at the shipping options for the hifimediy and unfortunately it will most likely bump up the cost of both dac+amp over your $60 budget by about $10. If that is too much to spend, I remembered the ELE EL-D01 USB DAC (around $20) which is liked by some people in the discovery thread, it's headphone out is powered so it should be fine to drive your iems. The only downside is that it is ordered from ebay and ships from China so it may take some weeks to deliver.
It's a large thread, so use the "search thread" function for ELE
Edited by wskl - 11/8/13 at 10:13pm