My boyfriend really needs some "Friday night date" clothes so I bought him a pair of jeans and a sweater at ExpressMen.
I think depending on your budget...
$35-75 dating under 6 months
$55-100 dating over 6 months
Then again, it could be more or less, depending upon your financial situation. Or you could take a trip together, pay for concert tickets, a theme park visit, etc., rather than something material.
For the man who has everything, I say go for an accessory having to do with his hobbies: a state of the art bike pump for the cycling enthusiast or a gift certificate to REI for the guy who loves camping; a gift certificate for a massage or a hair cut at an upscale salon, gifts that remind him of his favorite sports team or alma mater, etc. Homemade gifts and dinners are always appreciated; just make sure any homemade gifts aren't overly cutesy to offend their masculinity.
