I did the same thing (RE 4.5" superflex with 3.5" springs) but with the RE shocks also from 4x4groupbuy after shopping around. I'm happy with it. It also came with an AA SYE kit (Advance Adaptors [a well respected brand name] Slip Yoke Eliminator) and a Tom Wood's rear CV driveshaft. The RE 3.5 lift give you at least 4" of lift. A very complete kit that if priced out separately would have been a lot more expensive. I sold the sway-bar disconnects that came with it and put on a Currie Anti-Rock set-up. When looking at kits in the 3" and higher lift, make sure they include things like an adjustable front track bar, bracket for the rear track bar (you might end up having to buy an adjustable rear track bar anyway like I did), adjustable upper control arms (at least for the rear) if you're going to do the SYE/CV rear driveshaft route (as opposed to spacing down the skidplate), longer brake lines, extended bump stops, etc. If they don't include them, factor their cost into the "budget" kit(s) you might be looking at.
For example, for an AA SYE and a TW rear CV driveshaft, figure another $465.00 into your cost Advance Adapters Slip Yoke Eliminator Kit + TW Drive Shaft
when looking at lift kits that include it (the RE kit below) vs. most others that don't include it in the cost of their lift kits.
Here's the RE 3.5" superflex kit from 4x4groupbuy (mentioned above) with SYE, rear CV driveshaft, front track bar, extended brake lines, shocks, adjustable upper control arms/new fixed length lower control arms, etc. for $1835.00 at Rubicon Express RE7000-3 3.5 Super-Flex Kit & SYE Combo and Shoc
They sell the same kit but without shocks for less, and then maybe you could get cheaper shocks to bring the price down a bit. You (the OP) asked, and this is my recommendation. And I looked at other options (Black Diamond, Rustys, etc.) before getting this kit, and while others started out cheaper, their final cost grew once you started adding extras that the RE kit here included. Of course, only you can decide if these "extra's" are things you feel you want or need. Some people are happy with just four springs and shocks and lowering the skid plate.
Help I'm typing and I can't stop! I have to let it go...
So I would start at 4x4groupbuy.com and check their prices and what comes with their kits (especially their RE kits), and then compare to Pro-Comp or whoever you want to check out and compare with what comes in their kits (make sure you're comparing apples to apples). Let us know what you find and decide on.