Hi Son,
You can achieve this programmatically BUT depending how it is done it could screw your
SEO (robots seeing duplicate but the same content may mean your site is penalised).
Using server side scripting (PHP, ASP, etc.) you can check the domain for .com or .co.uk and load the appropriate price list. I empathise with your issue but long term two separate websites is the way to go and to have unique content on each (at least ensure page titles and a good deal of the product descriptions are different).
There is no short-cut to success.