Best thing I ever bought was a garden shredder, as it means brassica stems, broad bean & tomato stems & a host of other 'non woody' stuff gets chopped up & thus decomposes along with everything else.
On top of that, it's shredded at least ten of those builder's dumpy bags full of privet, dogwood cotoneaster & a host of other things which grow out of control if untended (I help friends out whose gardens have run amok in exchange for the material produced).
Many people don't realise how much compost is needed if you're going 'no dig' & fertiliser free, so consider this:
A standard allotment is roughly 250m²
Actual growing area (paths, sheds, compost bays excluded) will be around 75% of that, say 180m².
To provide the soil's needs & ensure a good crop, a 2.5-3cm layer of compost is required.
180x.03=5.4m³ of compost, every year. That's roughly 3 tons.
I have a mere 75m² of beds (including greenhouse & polytunnel) & this alone needs 2.25m³ of compost & despite 300m² of lawns, 60m of hedge, weeds, harvest waste, more than 400kg of shredded cardboard (industrial office shredder) & scrounging, I still only manage just over 60% of that & have to buy in either fertiliser or compost.
Heck, my thirty, 30 litre potato tubs swallow 0.9m³ of compost every year BUT 80% of that volume is recovered & as it's more broken down & with some added blood fish & bone, becomes the next year's seed, potting & bedding plant medium.
I have:
A twin bay, holding 1.5m³
A single large bay for another 1.5m³
Two 'Daleks' at 0.3m³ each
A .25m³ bin I'm using to make seaweed compost to try & replicate the Jersey Royal™ taste we used to have from International Kidney potatoes.
Bear in mind all these volumes reduce by half or more as the contents break down.
OK, I admit it: I find making compost almost as compelling as actually growing things.