Ebay is pretty cheap, you just have to be patient and hope they ship to the UK. With the current Pound to Dollar ratio you should be able to make out. I see used ones going for $200-300 US. The refurbished ones are twice that. Have you called Philips directly yet and asked about a battery? You may also want to search on refurbished Iprontos and see what comes up. As for other remotes that are this flexible look around the web site I guess. Some of the new Pronto remotes might work but they are smaller (and of course they are made by Philips always a drawback). I think the 7000 and fully customizable and color. I have the TSU3000 and can do what ever designs I want, it's just B&W. I have gotten great prices on IProntos and TSU3000s on Ebay, just gotta wait a while.
It seems the powers that be have determined users are stupid and should have as little control as possible over the remote. The remote will just do it all by magic. With the success of the Logitech remotes it appears they may be right.