How much danger in using non-Canon battery?

How much danger is there in using a non-brand battery?
A Canon NB-6L BATTERY costs $75, which is more than 10 times the cost of a non-brand replacement battery.
Page 33 of the SX260/240 manual says:
"Use of genuine Canon accessories is recommended.  This product is designed to achieve excellent results when used with genuine Canon accessories.
Canon shall not be liable for any damage to this product and/or accidents such as fire, etc., caused by the malfunction of non-genuine Canon accessories (e.g., a leakage and/or explosion of a battery pack).  Please not that this warranty does not apply to repaired arising out of the malfunction of non-genuine Canon accessories, although you may request such repairs on a chargeable basis."