We often are asked to fit second hand / reconditioned aga cookers and do so with pleasure, prices are on application but as a rule of thumb installation is usually £450/500 for most 2 oven aga's. Night storage (30 amp) aga's are more at £600 to remove and £650 to rebuild. Plinths are usually £200.
We also move existing cookers for customers to their new property, often reconditioning the enamel and new chromed lids in the process. When moved carefully and reassembled correctly there should be little or no change to the aga, in fact often they are better - depending the quality of the origional build.