I should ask you, "How Much Do You Want to Spend?"
A basic piece, such as you find in the Mark Wilson Course, will cost a couple hundred dollars to build and somewhere around $800.00 to $1,200.00 to own. . . more, if you go for the Walter Blaney variation and the like.
The Sharpe Encyclopedia of Suspensions & Levitations will give you about 1,000 or so different methods along with sufficient information when it comes to being able to build them. . . though, when it comes to such effects I DO NOT RECOMMEND YOU MAKE YOUR OWN -- levitations and suspensions can be very dangerous, I've seen the towers fall with the girl on them, I've seen girls "bounce" off the Sword Suspension and get seriously hurt. . . there are many other complications that can happen.
The other thing you need to ask yourself is "Where Will I Perform This Illusion?" What's available to you and how often will you be able to work that kind of venue? For most who are just starting out a Broom styled Suspension or Sword Suspension tend to be the more practical in that the angle issues as nominal, they both pack relatively small, rarely weigh more than 100-135 pounds (while the majority of the other "full" levitations run between 300 and as much as 1,500 lbs, depending on the lift needs).
You need to consider other things such as if you really need to pick-up a real girl or not; the Asrah Levitation is popular because it doesn't weigh a lot and depending on which version of the illusion you invest in, it can be done in a theater or a living room. . . I've owned at least six different versions of this one levitation over the years. You can expect to pay between $2,000.00 (very low end) to over $10,000.00 for a brand new top of the line theatrical version.
Understand too, not all magic builders deliver quality/dependable magic. Do some comparison shopping; not everyone that builds an AGA System builds with the same standards or materials. Too, there are several variants to the AGA styled Levitation unit, some requiring you to drill a hole in the stage floor while others require you to suspend the lift mechanism in the flies, so ask questions.
ONE OTHER THING. . . unless you have loads of money and plan on touring on a high yielding route, don't sock big money into the hoop. There are some available that retail for well over $1,000.00 and yes, they are special. There is however, no reason at all to buy one, if you can work the illusion the way you are supposed to, NO ONE other than a magician, is going to know (realize) that you've done anything "sneaky")
Hope I've both, answered you question and forced you to think a bit.
