Ok, Jackson does their model numbers as follows...
1 and 2, (kv1, kv2, sl1, sl2, etc) are if I am not mistaken, neck through models, meaning the neck goes through the body. It has better sustain and tone. Those go for somewhere around 1400 plus United States dollars. I have a kv2 and love it.
3 (kv3, sl3, etc) are not neck throughs. That doesn't make them bad in any way. I also have a ke3 (kelly), and it is also a very incredible guitar. I believe that was around 600 bucks.
BC RICH makes a very mean guitar. Warlock, Bich, Virgin, or Beast. For the money you are willing to spend, you could get a NJ Series Warlock, if you do, get it with a widowhead stock. I want a neck through version.
You could probably get a used Jackson or BC RICH neck through for that kind of money as well. Just make sure that the guitar is worth the money. Know what to look for as in neck warpage, fret wear etc.
I believe that with guitars, you get what you pay for... In most cases. My first guitar was a Epephone strat copy that went for aroung 250 brand new. That thing took abuse like you wouldn't believe. I threw it out in the snow, snapped off strings, slammed it down, etc, etc, and to this day, it still plays. I am willing to bet that if I put my Jacksons through such totrure, they would die.