You may find that the Dabs prices won't include the cash back voucher! As the price probably includes that already.
It may be a better deal here
Computemate prior to release you get 5% discount on the price of £57.99 plus you get the £15 cashback voucher.
Or here
Justflight and you get the casback voucher plus £10 voucher to spend at Justflight, price £59.99
Hope that helps.