I was lucky - I bought a hack back in 2005 who was a champion under sidesaddle and his previous owner gave me a ride to see if I liked it. Then there was a sidesaddle for sale at Canterbury Equestrian which the owner let me borrow for a month. That got me hooked. Then I bought an indian sidesaddle from America for about $1,000 which got me started and it built from there

What area are you in? You can contact the NZSSA, and depending on what area you are in, they often have members who will loan you a saddle or help you get started.