I doubt the quality of the blowdrier makes a difference. As long as it manages to blow air out, it should work, LOL. I think my hair drier is a cheap Conair too. I blowdry my hair every day and I don't have any frizz. I think how much frizz you have depends on the technique. If I just blast my hair with the blowdrier (even with the diffuser on, and even how they show to do it in the Curly Girl book), my hair will turn to fuzz. I use the PixieCurl technique instead. I take sections of hair, set them on the diffuser and set the diffuser against my head (like scrunching my hair, but with a diffuser). Then I turn the hair drier on. You can leave it on for 30 or 40 seconds, which I think is normal for the PixieCurl method, but I leave it on longer and switch back and forth between the warm and cold settings. That way, my hair doesn't get too hot, and I don't get the frizz I would if I were to be moving my hair all around to dry the different sections every 30-40 seconds. I then turn the hair drier off when I feel the gel starting to harden.
I think there could be a few reasons why your hair is frizzing.
1. You may not have the diffuser close enough to your head when it's on. You want to be sure that your hair is secure on the diffuser and there's no hair flying around from the blast of air.
2. You may not be using enough gel in your hair. Using enough gel is important for keeping your hair in place while it dries, especially if you're using a blowdrier. I haven't ever tried drying my hair without gel, but sometimes I forget to add gel on a spot and it will get frizzy.
3. You may be drying your hair too much. Even if you're using gel, if you dry it too much, the blowdrier will break the gel cast and your hair will be free to frizz everywhere. You should only dry your hair until it's 70-80% dry, and then let it air-dry. Also, try to dry all your hair before it the gel starts to harden, otherwise you'll break the gel cast and create frizz.
You shouldn't be getting any frizz when you blowdry your hair. But I think if you play around with your techniques you can figure out how to prevent it!