MKS (the only current manufacturer that I know of) does in fact supply hardware with their toe clips but it actually is pretty flimsy. Last time I picked up a new set of pedals I asked for an extra set of hardware just in case I lose something while on the road(which actually happened, thus my low opinion of the MKS hardware). What they gave me was the hardware for those god awful plastic toe clips which is surprisingly a million times better than what MKS gives you. It think it cost me 50 cents. I went back later and bought more to replace the hardware on my other clips.
You most likely will get by with what comes with the clips but trust me, this upgrade is worth it.