Purity Seals

Certainly  purity seals are the bling of the Inquisition, Grey Knights and Sisters of Battle. The question is can they get enough of them. The GW provides molded on purity seals on some minis and customizable purity seals for some such as Grey Knights. But if you want to up the purity and worship of the Dead Emperor stakes more purity seals are needed. There are a number of options to getting more purity seals to add to minis. ForgeWorld sell a packet of resin purity seals for £6.50 plus p&p. These seals are well sculpted as might be expected but are a bit pricey for what you get. 

Grey Knight Terminators and perhaps other Grey Knight plastic sets also have spare purity seals that can be used elsewhere.

Finally it is possible to make your own purity seals with paper superglue and some green stuff. Here are some made recently. 
 The pictures speak for themselves I think. Stick the bits of paper together

 Add the green stuff and depress the center with the end of a paint brush handle.

Undercoat and then paint.

And finally cut out of backing paper ready to apply.

To this.