I havent come accross p90x before but the kit looks pretty comprehensive! How is it going for you? I am lookig at getting a similar sort of video for my indoor cycling - although the name 'sufferfest' is pretty ominous....
Personal trainers can be expensive - although I knew someone who was starting out so got a discounted rate (
http://www.danakenheadfitness.com) , to be fair though I was pretty sceptical about how much a personal trainer can help me purely because I have been going to the gym and know a fair bit about working out but it turns out they a sports science degree is quite informative!! haha. Joking aside it was pretty useful to have someone to workout with because i usually do it myself and someone who knows their stuff inside out! A couple of sessions is not that expensive and you may learn something new.
On the flipside I also do a heel of a lot of exer4cise at home so the p90x is like a virtual personal trainer so if I had to choose between a full price personal trainer it would be a tough one because the full package with p90x is pretty expensive! I dont know if you have boot camp style fitneess classes in your local parks because that would help with not having to pay gym membership?
Either one is good - I suppose the most important thing is actually ddoing it!