As a rule of thumb, radio advertising is charged at a rate of approximately £2 per thousand listeners at one time. To clarify, if a show has 100,000 listeners at 10am, then buying a 30-second spot at that time will cost you £200. The late show's 10,000 listeners at 11pm would only cost £20. Generally, expect for a slot of 30 seconds to cost around £250 - £1000 per week, depending on how often your ad is broadcast and number of listeners.
Autosport is £1500 for a double spread but remember people dont read adverts, but do read stores.