We have a shop here that specialises in artificial plants....(they are also a small florist but most of their shop is silk/plastic plants) that I have found to be excellent.
They sell complete plants (some can be expensive, others not so much) as well as 'bits' of plants that can be bent/twisted/dismantled and 'hot glued' to existing logs and enclosure fixtures to add effect.
For example, I bought 5 stiff 'vines' about 60cm long for $1 each recently - They had a stiff flexible centre and could be bent/twisted around things. They made a lovely addition to my Bredli enclosure strung between the branches and 'twisted off' so they didn't move. He loves hiding amongst them.
I decked out my MD's enclosure with a 'grassland' theme for about $30. They had some small imitation eucalypt branches but sold out - When they come in will be buying a couple, breaking them up, and 'hot gluing' small pieces to the vertical branches in the Bredli enclosure so they look like the branches have trigs and leaves growing from it. This shop stocks a lot of native plants and different dryland grasses etc....
Try looking for an artificial plant store, or a florist that does dried flower arrangements and may have the bits and pieces - the smaller pieces that this store stock are the ones they use for decorative flower arrangements.