I found my first purse clasp in a Ribbon Embroidery Purse kit. I saw the holes in the clasp and thought "I could get a small crochet hook through there." I started out with very small beaded trinket/amulet bags and stone pouches without the clasps. I used same concept with the larger purses with clasps. The clasps are made by Bucilla. I have found a few different places to purchase these.
For the smaller change purse size, I first straight stitched with needle (large enough for the size 10 cotton thread) in the small holes all the way around with a ch-6 or so connecting on the sides. (Using same color thread as to be crocheted). Then to crochet in the straight stitches, I used a large blunt sewing needle and while joining the crochet thread, I stretched out each straight stitch (Waller out is what I call it) then the crochet hook will slide under straight stitches better. The 1st few rounds will be a little awkward, but as the rows go, they get easier to manipulate.
To make the ridges above the beads is done by crocheting in the back loops only. You can make these in all different lengths and widths. Some of my purses are done with the inner layer crochet and the outer layer bead netting.
I found some chains for them at an area craft store. You could also have a beaded crochet chain of many different types of stitches.