Over Christmas, I grabbed some trees off eBay, on the 'for that price, it's worth a punt" theory.
They're from an eBay seller called
everestmodel, who is based in China: they have 99.9% positive feedback in the 10s of thousands, and shipping time is 2-3 weeks.
For 20 quid and change, I picked up 16 6" high deciduous trees, which arrived today. They're clump foliage, pretty securely attached to a twisted wire armature: they do shed a bit, but not as much as some. And, in fact, they are pretty damn decent, all things considered. They will need some form of roots/base, but that shouldn't be too hard, and a thickish coat of something grey/brown to hide the wire twists (although from wargames distance you could get by without), but otherwise? Me like, and they're a good variation on the ones I've been making.