The Extreme is a set and includes the pump, a case and a shower strap. For me, the pump is pretty much essential. If you don't get the Extreme, I would try to source the pump as an accessory (not sure this is possible). Without the pump you have to push uncomfortably hard into your groin; with it it's easy and you can control exactly how much vacuum is generated.
Am I the only person that thinks you didn't need to make a 3rd thread regarding this subject. You could have just asked the question on one of your previous 2 threads. Or ring customer services and ask their opinions. Contrary to popular belief they are there to ask questions and advise, not just sell the most expensive product 'cause let's face it, it's LoveHoney with their 365 returns policy - it doesn't benefit them in the slightest to sell you the wrong product and have you return it a week later in an unsaleable condition for a full refund....