If you add WW2WW to the mandatory list it significantly reduces choice. As far as I can see it is a choice between Savvy and GenRight Mini Boat Sides, and if you are going either of those routes they do not come cheaply, even in the US. Barnes 4WD do a WW2WW inexpensive option, bit it is attached to the body mounts which I guess counts it out.
I had a go at trying to update your original summary into a more simplified, tabular form. I have only done this for a few of the options and there are a few gaps still...
| Savvy | | ARB | | Warn | | Poison Spyder | | Barnes 4WD | | RT Offroad | | GenRight Mini Boat Sides |
Rocker Guard Material | ?/?" Aluminium | | 1/8" Steel | | 3/16" Steel | | 3/16" Steel | | 3/16" Steel | | 3/16" Steel | | 3/16" Steel |
Underside Fixings | Bolts | | Bolts | | Spacers & Bolts | | Body Mounts | | Body Mounts | | Spacers & Bolts | | Bolts |
Step / Slider | Y | | Y | | N | | Y | | N | | Y | | Y |
Step / Slider Material | 3/16" Steel | | 1 1/4 Sch 40 | | n/a | | ? DOM | | 3/16" Steel | | 3/16" Steel | | 1 3/4 .120" DOM |
Backer System | Y | | Y | | N | | N | | N | | N | | $39 option |
WW2WW | Y | | N | | N | | N | | Y | | N | | Y (req's trim) |
Underside Shape / Transition | Double Bend | | Double Bend | | Curved | | Single Bend | | Single Bend | | Single Bend | | Double Bend |
Weight | c.69lbs | | c.65lbs | | ? | | c.74lbs | | ? | | c.65lbs | | ? |
| | | | | | | | | | | | | |
Domestic US Cost (ex. Shipping) | $700 | | $415 | | $415 | | $502 | | $250 | | $170 | | $800 |
I have used Quadratec prices where they sell them, and the manufacturer's price where not. It seems in the three years since your original post costs have risen quite a lot in some cases.
As ever, the choice for me is different due to the cost of shipping. GenRight won't quote online to ship to the UK, but I did look at Savvy in the past and the cost delivered to me, incl. import taxes, came out at just short of $1900.
In the UK, as far as I can see, I can only buy ARBs, Poison Spyder or RT Offroad. The Poison Spyders are out due to body mounting, but out of interest they cost over $1700 in the UK. The ARBs (questions pending on robustness of materials) are just under $750. The RT Offroad option is available for about $260.
My thinking is therefore to get the RT Offroad and buy some aluminium to use as a backer plate as suggested further up this thread by Jerry. With the cost saving versus the only two viable WW2WW options I am pretty sure I could find somebody to weld a small extension piece on each end, but to be honest I will probably just live with the risk as the terrain here is typically not charaterised by big rocks.