Initial investment for 17 vehicles may be tough to sell...
but I might be able to pull off getting 3 or 4 at a time.
What are the drawbacks or extra charges I would incur if I did it in a piecemeal fashion? (besides the normal cost of the device and additional monthly subscription fee)
Would I be missing out on an additional discount?
There aren't any drawbacks or extra expenses for ordering 3 or 4 at a time vs ordering all at once. Price breaks for monthly service start at 3 devices and each time you add more, regardless of the quantity, the monthly cost will be just ~$6.70/month per device added plus cost of the device. We offer free 2-day shipping on our site so you won't be charged for multiple shipments whether you break it up into two orders or six. (Note, we are experiencing delays with Amazon so ordering on our site is preferred)
We're always happy to answer questions, simply reply here or use the chat feature on our site.