For something a bit out there, you could try the Reaper Raptor Pack for getting some mounts.
Good idea! I have some old Lead Boiler Suit Company raptors that have not been used much for ages. Hmmmmmmmmmm.
Set me thinking ... terror birds? Thingiverse has some and son has 3d printer ...
EDIT: Just tried a "dry fit" of the goblins on the HLBC Raptors and with a suitable saddle they should fit.
so choices?
Dark Alliance Wargs (approx £10)
3d printed Terror Birds or Raptors (small cost)
repurpose 11 HLBC raptors (no cost)