The best thing is to look in your local area. There may be an independent supplier who can offer a good price, and if they have to make deliveries to you it will be better the closer you are. The yellow pages are your best bet here, or else put 'wallpaper suppliers' plus your nearest big town in a search engine, and different suppliers will come up. Also, try using different search terms such as 'decorators merchants' 'wallpaper wholesalers' etc. Most of them have a website as they rely heavily on online custom.

You may also find that a big national supplier such as Brewers will fit your needs. These usually have branches all over the country, and you can develop a good working relationship with a local branch even if it is a big national store. Joining a local business organisation can also help with finding new ideas and sources.