As someone who has worn long hair (every length possible for me) and various wigs for many years I'm pretty qualified to advise you here. For starters, nothing comes close to looking as good as your own long hair. If you've got some hair, start growing it. Be who you are. If you love long hair make the world get over it and live with it.
As for wigs, this all depends upon what you want to do. You don't say whether you're going to out and around or just looking at yourself in the mirror at home. If you're just staying at home, you might be fine with any cheap plastic wig. I've owned a few synthetics and here is what I've experienced. Blonde synthetics almost always look phoney as heck. Darker synthetic wigs can be styled to look OK. I never wear a synthetic out of the house, though.
The most convincing wigs are the human hair type, which cost more. And no matter how tactfully you style one, if the wig isn't the front-lace type it will probably look wiggy because of the hairline. There are also great differences in the quality of human hair used in wig making. Some are quite stiff and hard to style while higher quality human hair (usually the most expensive) can have a very beautiful texture.
However, human hair wigs have to be carefully cut and styled and maintained or they'll look like an old mop. Buying the wig is just the beginning. You need to learn to care for it, too. Since the hair doesn't grow back, wigs must be handled much more delicately than one's own hair.
That's something for you to start with. I can answer further questions if you have any.
