When considering measures to protect your home from water damage, it's important to keep in mind that the are two types of work that can be done: internal basement waterproofing and external basement waterproofing. The first, while less expensive and easy for an amateur to do, is much less effective at countering the ravages of hydrostatic pressure damage on your basement walls.
External waterproofing, on the other hand, is the optimal way to completely protect your basement from flooding and water damage. External foundation drainage systems consist of perforated footer drain pipes that circle your basement and move excess water away from your home, depositing it into a storm drain or other location. Rainwater is directed toward the footer drains by overlaid limestone gravel, which has excellent drainage qualities.
Unfortunately, in order to install, repair or replace footer drains, large amounts of excavation with heavy equipment is needed around the foundation of your home. This is why exterior basement waterproofing is so expensive: the equipment used and the man hours required add up to a hefty bill.
Properly maintaining your footer drains isn't something that can be ignored, though, especially if you live in an area that has high yearly precipitation. Look at it as a way to protect the equity in your home; it's likely that any new buyer will order a basement waterproofing inspection if they are considering your property, and a quality drainage system will make them more likely to buy.
Of course, the most important reason to make sure your exterior waterproofing system is in good order is a simple one: the protection of your own family and property. A flood can be difficult to deal with both emotionally and financially, and spending the money to prevent it from happening in the first place is a good way to preserve the value of your home and the comfort of your family.