Bru,

you could get a good quality 135 A/h Agm battery for about $235 delivered.  You'd need to work out your power draw to decide how many batteries you'd need, most people have 2 but need to also consider weight cause they's weigh about 35kg each.  Then allow $250 for some lights and some cable/wiring, circuit breaker + fuse box, 2 to 3 12v sockets.  With the lights, if the 12v wiring inside the van is OK, then converting the existing lights might be a cheaper/better option.

edit typo

-- Edited by madaboutled on Wednesday 6th of January 2016 12:41:53 AM

Thought of all 12vDC system ? Leaving 240v AC for mains ? its hardly worth it these days as wont have enough solar or battery to run 240v for any length of time.. phones etc can be charged off 12V.
I have converted T.V, lights to LED and only use converter on microwave ..
If your able to fit yourself ? You'll save quite a lot..
Search YouTube there's so much info and how to on there .One of many...www.youtube.com/watch
I suggest using the larger size cables if you can..
At a rough estimate I would say $800.. $250 battery, $300 solar with fittings, $150 for controller...
$80 wire, breakers, fuses etc.. I used alloy angle plate, pop riveted to panel $7 from Bunnings and stainless screwed to roof with generous coating both sides of sikoflex..
Run solar wires down vent or fridge vent...