There are a LOT of good quality variables you could get for that kind of money...in a 1" tube.
The super sniper is a great scope for $300, and it is a 30mm tube...which is important for what you *might* be doing. The problem with a fixed power scope is that if you get a high X one for 800 yards, say 16 to 20x, it's really tough to shoot it at 100 yards. I wouldn't go any higher than 10x in a fixed, but that's just me.
At 800 yards you pretty much have to have a 30mm tube to get enough elevation adjustment...now that will cut down on what's available, since 30mm scopes tend to be a whole lot more expensive than 1" tube scopes. You'd be hard pressed to find a good 30mm tube variable scope of that magnification for less than about $850 or so...that includes Nikon, Leupold. Burris just came out with their Extreme Tactical line, which is in your budget...very nice looking scopes, 30mm tubes, but max X only to 12. Also, the Burris Black Diamond is available in the 6x24x50 model..it's a 30mm tube, with target turrets and a mil dot reticle, for around $700. The 50mm objective is pretty big, requiring higher rings.
Given the urban sniping profile you mentioned, how realistic is it to have to worry about 800 yard shots?
If you stick to more realistic ranges, you could drop down to a 1" tube and give yourself a LOT more possibilities. A 3x10 or 4x12 would work fine, and you could easily find one of those in a Leupy, IOR, Burris, etc. Pretty much all the major scope manufacturers are gonna have what you need in a 1" tube for your budget. I'd look for something with a mil-dot reticle, or some other form of ranging reticle. I'd stick to a "tactical" style scope, to maintain the profile of a LEO/military look.
There are several vendors who support this site that could help you out when the time comes to buy.