this is my experience as a relative newbie myself but I would go for the cheap T ring adaptor that fits your camera so you can then slot it into where the eye piece (prime focus)fits. I have personally found it easier to do this first because when you add a barlow your mag goes up, field goes down and your stars/planets start moving a lot faster through the field, which if your tracking is not good then you are chasing the images all the time.
And you can always add a barlow later.
Have you also looked on ebay? usually very cheap T adaptors as well.
Have fun
Graham
