I want to know what I would need to be able to record 2 seperate tracks at the same time but still be able to edit them independently.

For example a guitar mic on the amp and another in the room away from the amp. Then I could blend the two together and get the volumes, etc. correct

All I have now is a 4 track Tascam DP004 (i think) and my buddy has a mixing board that he runs into his PC. But the PC can't seperate the tracks obviously cause they're both coming out of the mixer on 1 output. My Tascam thing is decent for ideas but I wouldn't really use it for recording a song.

So is there anything without getting too pricey that can do this?

How much is pricey? The Line6 UX2 would be able to handle two line-in guitars or two microphones with phantom power and runs somewhere around 200 bucks, but you'll grow out of that once you start looking to mic a drumset, record more than two instruments at a time, or use more than two inputs at once in any way.

I have a ZOOM R16, which acts as a USB interface and a standalone recorder... And can be linked to another R16 to get 16 inputs at a time, which is more than enough to get live drums, but it cost me 500 bucks for one.

Some interfaces to look at:

Focusrite: http://www.focusrite.com/products/

Line6: http://line6.com/products/recording/

Zoom (Refer to the right hand side under handy recorder and music production tools)
I was in roughly the same situation a while back. I just went all in and bought a Tascam US-1800 and couldn't be happier lol. Granted that I needed to record a drum set with at least 5 mics.
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I have the Saffire 6 USB from Focusrite, it is 2 in/ 4 out, so that would work, and it also comes with a lite version of Ableton, I believe so you have a multitrack(digital) to record as many as like, something to think about about 200 bucks or less, just shop around, also known for their great pre-amps!
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it comes down to cost. when you say, "not too expensive," what do you mean? a simple two channel usb interface is going to run you about $200, which is all you need for just two inputs. if you want more inputs, the cost starts going up. you can get around 8 mic/instrument inputs for $5-600. in the grand scheme of recording gear, thats not a ton. but if cheap for you is more on the order of $200, you can do what you want. for less than that, probably not.

so if you can narrow down a price range, it might be easier to find something with the right features for you.