Those plastic ones will definitely work. For a slightly more secure feeling, there are MKS metal clips for about $12 new. I use metal clips with inexpensive nylon straps from Nashbar ($4 for 2), but may upgrade to nicer straps one day. I don't like the way leather can weather kinda poorly sometimes.

It looks like you may need to pick up 2 washers and 2 nuts, from those pictures, if the person doesn't include them.