Your price range is a little restrictive, but with the market being depressed as it is right now, there are some good choices, but your preference for a non floating trem is going to be too restrictive, so I will ignore that in my recommendations.
Look to get a used Ibanez RG7620...this may take you slightly over your range, but it will be worth it.
After that I would check eBay for Carvin 7 strings, either the 747 or 727...great guitars.
Next I would consider an ESP LTD H-307, or 207....or a Schecter C7 or C7Plus....or a Ibanez RG7420.
The Ibanez 7620 has a much better trem and the neck profiles are more comfortable. *THe carvins are neck through designs with excellent playability. *The LTDs are beefier necks, the 307 is
neck thru. *The Schecters have fat necks too. *THe 7420 is similar to the 7620, but it has a TRS trem instead of the Lo
Pro Edge 7.
The Petrucci is going to run you upwards of $2000 depending on options. *You should have no trouble finding a 7620 for around $500 or less.
