Chrissie,
I know this is out of your area but can I suggest that you contact jacki at beacon alpacas on
http://beaconalpacas.co.uk/before you commit. Jacki is a well respected experienced breeder who has appeared on TV and will give you some sound advice without a hard sell. Alpacas are beautiful but really dont like being in close proximity to humans which makes routine tasks a real challenge. There are books available by alpaca training experts on how to work with them but its abit like horse whispering and takes time, understanding and patience.
I dont want to put you off them as many people keep them successfully but I think it's worth doing a bit of research before you commit. You can go on courses to learn more about them you know what you are letting yourself in for. From my limited experience ( of being asked to train other peoples ) I do know that people are often keen to get rid of the more flighty ones which make catching the others even more of a challenge so make sure that any which are offered for sale are what you want and not just somebody's pain in the @rse.
You pay a price for good quality animals of good temperament so a cheap one may not necessarily be the bargain it appears. Ask jacki about health issues too and TB.
They are also a challenge to shear and even my good natured ryeland sheep shearer wont touch them. So ask about shearing too.
Good luck with whatever you decide.