Yes, Amazon vouchers are completely OK, it's a standard thing to do and it really helps to increase response rates. It does not make your research look less serious - I have worked on a survey where they had price draws for respondents and prizes were a weekend in a wellness hotel (for 2 persons!), TV, Ipod...So no worries there! As most of us don't have funds to offer holidays and Ipods, Amazon vouchers are an affordable alternative. Also, offering the respondents to give money to a charity in their name (maybe even a charity of their choice) could be a nice idea? Perhaps you can let us know what you did and how it worked - increasing response rates to surveys is always a hot topic! (up) Good luck!