What were the hardware specs on the mac?
Cheaper alternatives would be gaming laptops or high end consumer models.
Gaming models can be found from the following companies: Asus, Sager, MSI, Dell and custom boutique vendors
High end consumer models you can find at pretty much every big company today, Dell has XPS series, Toshiba has Qosmio series, etc
There are probably custom vendors in England too, but any specific names escape me.