I started out with a 1m2 box trailer which I had bespoke made by a local trailer builder, it was big enough to get everything in. I used it for over a year on the back of a Peugeot 405, it's still sat in the unit if anyone is interested in it, hasn't moved for probably 3 years but is in A1 condition, carpeted inside and cargo rails on side for bungeeing everything up.
I'd recommend going for a trailer if money is a bit tight, set up is probably less than the cost of the insurance on a van.