postcard.co.uk

I have what appear to be 7 x Valentine's proofs or reference cards as they carry the same number as on the finished colour postcards produced by Valentine's. These are in black and white and are plain backed cards. I have been in contact with a Bonzo website and Richard who runs that site also thinks its likely they could be some sort of Valentine's reference or proof card.

I am a bit out of my depth with pricing on these things - they are a bit out of my comfort zone! So before I put them in my postcard shop where I would probably end up setting the price either too high or too low I wouldn't mind any input.

Here are scans of 5 of them:

These look more like salesmans samples than proofs - proofs would be full colour. While they're quite unusual, they're not especially rare.