I recently ordered some trees from an ebay seller based in China. These trees cost £X including postage to the UK.
The bases were textured, painted (brown then dry brushed) and flocked with a woodland undergrowth mix.
The finished forests. The trees can be removed to allow space for multi-based figures, and they can also be taken off to use without the big bases.
Here they are in action. A couple of days after I'd completed them we played Bolt Action and the new trees were put to good use.