I'd suggest getting a general purpose taper WF line in a 7 wt. These lines cost about $40. Use that line to learn to improve your casting skills, then invest in one of the specialty line designs. You'll save money in the long run by going that way.
This is the first I've heard of something like this and I find it pretty interesting.
Most of the fly line manufacturers offer several levels/grades or whatever you call it of different fly lines. Their top end lines will have the latest and greatest plastic compositions and coating formulas. Most of them also offer a budget series of lines that you'll often find in retailers that have limited fly fishing equipment. The budget lines can save a trip when something bad happens and you're desperate, but otherwise I try to avoid these lines.
In the middle of these two extremes, many of the line companies offer a series of lines that can be good bargain. They seem to be the previous generation of coatings, plastics, etc., but for many situations they work great. I get the premium lines when I know exactly want I want, but if I'm wanting to experiment, I'll get these mid range lines.
TFO offers a fly line under their own name for about $40 that is made by Cortland. I have been using some of these lines for a couple of years and have been very happy with them. Somewhere on this board, I posted a review of them.
A couple of other examples. SA used to call their mid range lines the "Supra" series. I have several of these that are sinking lines. It looks like SA now calls this series the "Frequency" series. If you can find one the SA lines that has Lefty's picture on it, they are good general purpose lines.
RIO used to call their mid range lines "Mainstream", but it looks like they have moved them down a notch and introduced the "Avid" series as the new mid range line.
This is just another option to think about. If I was going to Alaska or Easter Island or some other expensive destination, I would take premium lines, but the mid range lines have been working well for most of the fishing that I do. Some folks may disagree with my opinion.