Jen, ask for secondhand in the classifieds first. I'm sure you'll save some money. The only risk is receiving a badly worn T-ring, perhaps?
ps, if you are buying new, see if you can extend to one of these:-
http://www.myastroshop.com.au/produc...sp?id=MAS-055A
I'll bring one to SV camp if you want to have a look.
You still need the T-ring as well.