If you are needing to create a spider faction or need spiders as mounts /monsters this is a great boxset to jump in on from Wargames Atlantic.
In the box you get 12 Giant Spiders and 12 small spiders for a total of 24 models. There are no bases in the box, but the value you get here is quite good for all plastic miniatures. (which you are familiar with if you have any Wargames Atlantic boxsets.
Giant Spiders
from $34.95
This hard plastic box set allows you to field up to 12 Giant Spiders, 12 smaller spiders and with sci-fi part options for every giant spider in the box.
Lets look at the strengths of this boxset. For the price you are getting a good number of miniatures and the Giant Spiders you can adjust the leg positions, thorax, and abdomen. The lesser/little spiders you can not adjust the poses, but Im certain you could do some bending or customization if you really set your sights on it.
What is nice about this boxset is the futuristic options that come with it. Whether its bioguns or mechanical bionics/parts this set has a good decent number of them to get you going.
Overall the Giant Spiders Boxsets is just what you would want to create some spider mounts for your goblins or to create your hordes. Its also probably a great place to get some parts for kitbashing spider parts you may want or need.
The biggest downside are the little spiders which are not posable, but if you know that going in and the Giants Spiders are your focus (which they are most likely), your all set.
Here are some additional pics to check them out.