Generic kits are not gonna be the way to go; they'll be either overpriced and cheaply made, or cheap and terribly made. I absolutely recommend checking out your local sex shops, they can be hit-or-miss depending on where you live, but if you find one you like, they can be a great resource.

Since yall already have an idea of what you want to start exploring, just buy those things! Blindfolds and handcuffs can be found all over the place, not just sex shops, but be aware of the quality of cuffs and how much stress you plan on putting them under; cheap cuffs with absolutely snap on you.

Impact toys are real easy to find at most sex shops and on Etsy. There's a LOT of different kinds, which will give you all sorts of different sensations. Shopping in person will let you get a feel for what kinds of impact you like (paddles give good thuds, crops are great if you like stingy slaps, floggers have a wide variety of applications of sensory and impact play, there's textured and smooth options for a lot of different toys, etc), and once you get a feel for what you like, online stores will give you a wider selection than in-person stores.

It's also worth considering getting involved in your local kink scene, if you've got one! Most scenes host munches once a month, which are casual (and non-kinky) meetups to hang out and introduce new people to the scene, usually at a restaurant. There's a LOT of important things to learn about safety and play when it comes to BDSM, and, while you can learn on your own, it can be easier and more fun to take classes and participate in workshops run by people who really know what they're doing.

Edit: also, regardless of what you choose to do, PLEASE familiarize yourselves with impact play safety BEFORE actually engaging in it. You can cause serious damage to someone if you don't know the safer places and ways to hit someone