I'll start off by saying I had the RCX kit on my 1500 and I was very happy with it. It rode just as good as stock if not better because of the added Bilstein shocks and the quality of the lift kit is right where I expected it to be. I didn't have any issues whatsoever with the install or drivability afterwards.
Now there are some guys that do have problems with the RCX kit. I'd say maybe 5% or less. As long as you're careful, order the right kit (and verify that when you get it) and know what you're doing you shouldn't have any problems.
The BDS kit is definitely a step up from the RCX kit. Whether or not it's worth the extra money is really up to you. When I lifted my 1500 I decided it wasn't with where I was at and what my plans were for the truck. But if you plan on keeping your truck for quite a long time then I'd definitely consider the BDS kit. You do get what you pay for, it is higher quality.
Zone is made by BDS and really the sole purpose of it is to try and compete with the RCX kit price wise. It's essentially a cheaper, lower quality version of the BDS kit. So personally I would take that one off your list. It isn't worth the extra money over the RCX kit IMO.
No matter what kit you get you will most likely want Bilsteins to go with it. So just keep that in mind when you're looking at prices. Contact the guys at Bully's Performance for pricing on any of the lifts and accessories that you want. Mention that you're a forum member and they'll hook you up with great pricing on it.
As far as your budget is concerned I have two questions. 1) Do you plan on installing the lift yourself? 2) Do you need wheels and/or tires when you do the lift that need to be factored in to that budget? Both those things are pretty big items that will effect what you can get done for $5000.
To give you an idea of what it will all cost here's what I spent on my set up on my 1500. Keep in mind I live in Canada so I pay extra tax on the parts. So take 12% off my numbers.... I also did all the labour myself, these numbers are parts only.
RCX Lift, kicker bars, and Bilsteins: $1900
Front end alignment: $130
20x9 Wheels and 35x12.5 Toyos: $3300
Flowmaster cat back exhaust: $650
Tint (quote): $100
So that right there is already close to $6100. Obviously the wheels and tires are more than half that though. So if you don't need those that really helps. Then the BDS kit would be more if you go with it and if you need a shop to install it you're looking at around $900 for install.
Hope that helps answer most of your questions. Post back if you have any more and I'll try to help you out.