Backcountry offers the Mountainsmith K-9 Combo for $13.49 plus $5.95 for shipping. That's $36 off list and the lowest total price we could find. It features an 18" collar with a 6-foot leash and a collapsable water bowl. comes in size S/M.
Of note, it's also available in size M/L for $1.50 extra. This extends the collar to 23".