Hi Aaron,
Apart from it being a 4-channel instead of 2-channel, you should seriously consider the BeatMix 4. It’s slightly more expensive … BUT … the full version of Serato is still included for that price. And if you have to buy it seperately (and really, the intro/LE versions are really only simple starter versions and you’ll want the full version really quickly imho) it’s a 125 USD upgrade! In the end the price for a BM2 with full Serato upgrade might end up costing you more than getting the BM4 from the get-go.
Just my two cents and I understand all about budget limitations.