I live in Washington and pay about 10% sales tax on most Amazon purchases. Even with the tax they are usually cheaper (especially with Prime shipping) than my New Egg or other retailers.
If you're a retail junkie it doesn't matter, an extra 10% won't stop you. It's like when cigarettes were $2 a pack everybody said they would quit when they got to $3. Here they cost about $9 a pack now and you still see people puffing away.