Alot of the Personal Plate brokers have domain names, some very nice ones actually.
This is their contact page anyway if you havnt already found it:
http://www.regtransfers.co.uk/main/contact.asp
I have always found that they set quite high end user prices and are quite happy to sit on them until they get the prices they want (Thats plate brokers in general, I have never dealt with regtransfers)
I guess this comes naturally from the way they operate with their number plate stock.