Arda has great Spikable wigs on their site. A wig that works well w spikes must be full but also have the wefts partially sewn in backwards. This is what allows for the good spiking base. I really wouldn't recommend an eBay wig for this....
Adelheid (KHR!)- 85% done
Fem!Austrian War Succesion France (Hetalia/Nyotalia)- 10% done
Fem!Izaya (Drrr!)- 90% done
Magent!Teto (Vocaloid)- 95% done