No matter how you slice is, unless you are getting coilovers for free, a leaf spring swap will be cheaper.
However, a traditional coil, when setup properly will be very close to the cost and has the potential to outflex a leaf spring setup. It will also excell in other aspects.
Flex isn't the only factor to consider when swapping suspensions.
You should also consider:
1) Approach and departure angles
2) Pinion angle change during flex
3) Axle wrap
4) Stability characteristics
5) Frame limitations
A leaf spring setup will not allow for best approach and departure angles.
A leaf spring setup is more difficult to get proper pinion angle change.
A leaf spring setup will wrap up.
In terms of stability, that depends on where you mount the springs (leaf or coil). Without a sway-bar (Anti-Rock) the leaf will probably provide for better stability, but at the cost of flex.
You will encounter frame limitations with any setup.
The bottom line is that you should go with what you want, what you understand, and what you can afford.
I disagree that coilovers are overrated. I think the phrase should be re-worded to say that coilovers are over-glamorized. People think they need them when in reality a traditional coil and shock setup would work perfectly.
Swap came out good.

Any close up pics of the brackets that aren't so blurry?