Cheap suspension forks have two problems:
1) they do not have any dampening at all, except for some plastic bushings that are friction-fit. When those wear out, the forks pogo up-and-down-and-up-and-down-and-up-and-down, all the time. Making new bushings requires tools that most people don't have.
2) they will also tend to squeak after not-very long (which you will quickly notice, since they will also be springing up-and-down all the time by then!) and replacement parts are not available. Taking them apart and greasing the insides may help the squeaking, but makes the pogo-ing even worse.
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What I would suggest is looking around online for some clearance Rock Shox forks. You want the low-end model from one or two years ago, these get priced out at around $150 and are MUCH better than the generic junk. Get one that has fluid dampening and try to see if you cannot get some replacement bushing sets at the same time. Look around online for comments on what parts fail, and try to get a couple changes of that part.
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