I'm not a big fan of just having a ton of toys. They will get old and yucky after awhile even if they're not used.
For me, these would be a few of my "must haves":
Condoms for all sizes of penises - average, large and snugger fit
Lube - I'm getting away from some of my favorite flavored ones and going with Sliqued and other organic types that don't have sugar included in the ingrediants.
Aneros - A must have. VERY well made but a bit expensive. I just use the old fashioned medium one.
An hitachi wand - for you and him
A couple of larger dildos - strap one, medium sized and a much larger one for those that might need it.
A couple of bullets (Make sure they're safe to use on men. You need a cord.)
Medical use (disposable) gloves - the black gorilla gloves are kindof cool. I just pick up a box at the CVS.
Feathers, silk scarves, soft furry things to use on their skin.
A few floggers, paddles, handcuffs, ankle cuffs if you're so inclined.
Leather and cloth shoe strings for cock rings that will fit anyone. Or a cock and ball tie up. Even vanilla men like this. You can tie up their cock to keep them hard.
This list is a start. Dallas has a nice arsenal, doesn't she?
edited to add: I have a lot of BDSM stuff for alternative play, and several items that I personally adore, that I haven't included on this list. That's rather personal in terms of what you might need or not, dependent upon your activities. I just listed what I consider mostly vanilla items that I would consider a necessity. Have fun shopping!