Here is a problem that you will most likely come across if the skylight that you have purchased is of low quality - the need to replace it. The key thing to know about in this case is when to replace your skylight. If you find that it is constantly leaking in several different places, you may want to consider replacement. If the frame is showing signs of falling apart, then, again, you may want to consider replacement. Naturally, the decision to replace a skylight is one you will probably be hesitant to make, as the costs involved are rather large. What I would say is that it's best to replace the skylight before its condition becomes a nuisance. When replacing a skylight, always consider why you are replacing it, and if this will affect your purchase of a new one. For example, if the skylight you are currently using must be replaced due to low quality, you should buy one of a better quality. If the one you are using must be replaced due to an accident, you should take measures to prevent that accident from happening again in the future, or buy a skylight that is particularly resistant to damage; it may cost more, but it will save you money if your skylights are unusually accident-prone. Finally, the costs of a full skylight replacement. These should not go beyond approximately $3000, or $2500. These are rather large amounts of money, that is the reason why I always recommend you buy high quality. It may cost $100 more, but it'll probably save you a few hundred dollars in the process.