I bought a $5 harp and it plays poorly. Can you fix it up and make it play better? What brand of harp do you recommend for a beginner?
I can't fix the cheap harp. Although it may be branded as a Hohner or Suzuki instrument, these harps are awful to play and do not have the potential to be improved - a terrible choice for a beginner. What harp to buy? As a general rule, I suggest you buy a harp that was made in Germany or Japan. I also suggest you buy a harp that can be taken apart with just a screwdriver if you need to set it up to your liking.
Harps that meet those criteria and are affordable include the Hohner Special 20 or the Suzuki Harmaster/Delta Frost. They are easy to find (in stores or online) and the quality is usually consistent. A good place to start.
I would encourage you to eventually buy other types (Seydel 1847, Lee Oskar, other Hohner Handmade harps like Marine Band, Blues Harp, etc...) Anyone who starts playing harp rapidly gets addicted and soon finds that they have bought a collection of instruments in various keys and from various manufacturers. Take your time before deciding that you want to stick with one particular make or model. It's good to change things up; for example, Seydel harps have wider spaced holes than other brands and that may take a week to get used to. That's a good exercise for your muscle memory as well as your brain. And overall, that workout will make you a better player.
The advantages and disadvantages of the various kinds of good-quality out-of-the-box harps fall into two categories:
1- deficiencies such as the harp not being airtight, not being set up so that it is easy to play, or being out of tune.
2- matters of preference such as the size of the harp, the material it is made of, the shape of it in your mouth, shape of the cover plate.
All out-of-the-box harmonicas will have deficiencies. Some less that others but you can't expect a store-bought harp to be perfect. As a beginner, you need to figure out if you are having trouble playing a certain note because of your technique or because the harp is leaky or not properly set up. Even the most expensive out-of-the-box harmonicas suffer from this problem. That's because it's not feasible for the harmonica companies to mass produce harmonicas and give each instrument enough attention to ensure that each one is precisely set up. That being said, there is no problem that can't be fixed, and part of learning the harmonica is to either learn how to fix them/set them up yourself or get a guy like me to do it for you.
It's a chicken-or-the-egg situation, since you need to know what a proper harp sounds/play like in order to tell if a harp is not in proper order. I recommend you get a harmonica teacher and take a few lessons to start - if you have a questionable harmonica, your teacher will be able to help you troubleshoot.
One last thing about airtightness. An airtight harp will always have a better tone than a leaky one. It will also play better, bend easier and give you a lot more control. No out-of-the-box harmonica is as airtight as it can be. One thing you can do to improve airtighness is to buy an aftermarket comb (the comb is the part in between the top and bottom reed plates). These aftermarket combs are made out of various materials and are flatter than the comb that comes with the harmonica. A flat comb will help make the harp more airtight. The stock comb can also be flattened by hand. But it's a lot of work. I put 20 to 30 minutes of work into making just one Marine Band comb flat and sealed.
Here's one last thought. I went to see a Curtis Salgado show last summer and I got to speak with him afterwards. I asked him what harmonicas he plays and he said "I'll play anything anyone gives me as long as it's in tune." Words to live by.