I have mine done at Mt Alvernia, but the $900 is purely for harmony test. As far as I know, the full complete test (including all options) only test for anormaly of the 3 chromosome and the sex chromosome. So if you've said HIV, then the amount you pay includes other test outside of the harmony test.
You've gotten your results yet? The results came back pretty fast though. Although they told us it's about 10 working days (i.e. 2 weeks), it we got a call just a little over a week with for the results. Indeed, worthwhile for peace of mind and a bonus for being able to know the gender so early.