I have 2 slots available on my account, I pay £79 a year and am able to add 4 family members. I add you as an aunt/uncle etc. and you get 12 months Amazon Prime.
Ideal if you can't justify the £79 price tag. You do not get the Prime movies but you can pick up Netflix accounts under the same sort of arrangement for £20(ish) on ebay.
If you don't know what Amazon Prime is, it gets you free, next day delivery on any item "Sold By Amazon" or "Fulfilled By Amazon".
Payment by Amazon Gift Card after set up
£15 gets you membership via my account for 12 months from setup.
Payment by Amazon Gift Card (Buy online and generate a code)
Paypal also accepted.