At the moment my Jetmax 250 has standard shocks with a 5.5mm spring wire thickness which mostly seem fine albeit a bit firm on setting 3 , I have never bottomed out on this setting.

With my wife on the back they dont cope when set on max setting (5) . They dont appear to sag much so seem to support the weight but hit a bump and it bottoms out on the stops and on occasion the centre stand hits on corners.
I took care of the center stand issue by putting extenders on giving an extra inch of clearance but it doesn't stop the shock from bottoming out.

I am not about to spend 1/3rd or more of the bikes price on olims or some other brand, I just need something better than it has.

I was looking at these for around $150. They are longer so no need for extenders.
Working stroke is similar as I have now but max loading I would think is considerably more.
Spring thickness: 7.10mm
Working stroke: 56.00mm
Max loading: 300kg / 650 lbs
http://www.ebay.com.au/itm/151582161...%3AMEBIDX%3AIT

These could be better again as they have a thicker spring and longer stroke but they are about 4mm longer than what I have now, which means I may need to mod the centre stand..
Spring thickness: 8.10mm
Working stroke: 70mm
Max loading: 300kg / 650 lbs
http://www.ebay.com.au/itm/YAMAHA-XV...item1e953259ee

They also have the same length/travel version of the above with a 7.1mm spring
http://www.ebay.com.au/itm/SUZUKI-GN...item234fbaf076
Eyes can be changed for toggles on request

Which ones?

Would I be right in thinking that I would probably be able to ride one up on the lowest setting and possibly have a less harsh ride compared to now and probably only need to go up a notch or two with the wife on the back seeing as they appear to have a higher max loading and a thicker spring?