At a minimum you are going to need a five gallon cooler, and honestly if you shop around, you'll find good deals on larger ones as well. You'll need the parts to convert the cooler. Either pre-built or using Flyguy's plans.
A large capacity boil kettle 7-8 gallons, but again 10 would be better. A ball valve in the kettle is nice, but not needed right away, you can empty the kettle with a racking cane.
A second pan for heating sparge water is nice, but not totally necessary.
A burner that is going to be powerful enough to boil everything. If you have a good kitchen stove, that might not be a necessity.
Rough estimate on costs.
Cooler: $25-35
Conversion Parts $20
Boil Kettle- $40-60 if you shop around
Burner- $40
All total, about 100-150 buck if you get everything new. Shopping around will save you a few bucks.