I currently have a pair of NE6's and Sunrise IEs, and an iPod Touch 3rd gen.
Would I benifit from an amp($100 or less), or can an iPod touch drive them just fine?
I too have the 3rg gen Touch, 64GB. Is there something you are missing in the sound signature with your current setup? Aside from the "headphone amps and other gadgets can be fun and cool" factor, which is definitely part of this hobby, first decide what kind of sound you like/want, and go from there. With my Etymotic ER-4P's, I didn't need an amp. I really didn't need one with the Grado 325's either. But after finally getting to know exactly what kind of sonic curve I liked, I settled on the Senn HD-650's. Well, those really needed an amp if I wanted to use my Touch as the source. I went for the TTJV Slim amp since I wanted a warmer sound sig. Let your needs and preferences drive your decisions. That way, you're more likely to end up making good and satisfying purchases. :-)
I'd be looking for more bass. Seems like I can only hear it on some songs, through my iPod, but can hear it better through my comp.
Are there any under $100, that I can carry around with me(without a comp.) that would be worth it?
What is your volume setting at on your iPod? If it's under half, there's no point in buying an amp. If it's over half but still well below 100%, there's no point in spending a lot of money on an amp. Maybe get something small like a Fiio E5.
Amps don't magically improve bass unless your current amp (your iPod) is rolled off in the bass or the new amp is colored. Some amps offer optional bass boost settings, like some Fiios or the Digizoid Zo. That would be the way to go if you do need an amp.
If the 3rd Gen iPod is anything like the iPhone 4, and I believe it is, since Apple never advertised the 4th gen stuff having better SQ over the last generation, the lack of bass should be because your computer is coloring the sound. The iPhone 4's FR is completely ruler flat.
Apart from an amp with a warmer signature, you also got the following choices
Use an equaliser app, like EQu
Get a different IEM with more bass, the Hippo VB is said to have too much bass by some bassheads
Attach car battery to speaker amp and walk around with subwoofers strapped to your head
They use their own power and shouldn't affect your battery to a noticeable degree
And if you use a LOD (I got the Fiio one from Amazon for < $20) your iPod battery will last a bit longer since the internal amp is not drawing from the battery.