sapele is more commonly used as an alternative to mahogany. it is a dense hardwood which is red in colour and easily sourcable. the cheaper alternative is another hardwood called meranti which is a lighter shade of red. brazilian mahogany is also sourcable, but is an endangered specie. go to www.lathamtimber.co.uk brilliant site for timber.
Maranti is actually what they term as a Bast***d mahogany, an offspring of mahogany and is sometimes (when the grain is right and the timber is properly seasoned) quite convinsing as a substitute.