Hi lifeiswonderful, I have recently bought Sonic Access though have only listened to two of the paraliminal meditations within it so far, they are excellent.
I find them great to listen to just before bed as they get me nice and relaxed ready for sleep. I think that its reccommends that you listen to just one Sonic Access paraliminal a day for optimal results.
Depending on your budget I would consider getting Sonic Access and also at least two of the others. New Behaviour Generator and Self Esteem Supercharger are the ones that I would reccommend.
For me the benefit of having the older paraliminals are that they have a shorter run time than SA and I find them better to listen to if I dont have a lot of time to play with. (Regular paraliminals are roughly 20mins long and the new SA sessions are around 40 mins in length - without listening to the music track at the end of each). Its great to just slip them into my day occassionally whenever I have a little spare time, and for me Sonic Access is better when I have a little more time to relax and listen without any distractions. Not always easy when you have kids!
Once you have made a first purchase you should be added to the mailing list and will hopefully receive offers from time to time that will allow you to buy programs etc slightly cheaper with a customer code in the future.
I hope that this helps... Theres so many paraliminals, it can be quite overwhelming and its easy to be spoilt for choice
Simon