Yup, I did factor that in. Otherwise the picos would be cheaper at 1 device since they are less than half the cost. 
If you're interested in how I came up with that number, here's a table of the spreadsheet I used. I just happened to not have closed it yet (since I wasn't planning on save it. 
)
| Pico | ||
|---|---|---|
| Startup | $100.00 | |
| Per device | $12.00 | Per device cost |
| 1 | $112.00 | $112.00 |
| 2 | $124.00 | $62.00 |
| 3 | $136.00 | $45.33 |
| 4 | $148.00 | $37.00 |
| 5 | $160.00 | $32.00 |
| 6 | $172.00 | $28.67 |
| 7 | $184.00 | $26.29 |
| 8 | $196.00 | $24.50 |
| 9 | $208.00 | $23.11 |
| 10 | $220.00 | $22.00 |
| 11 | $232.00 | $21.09 |
| 12 | $244.00 | $20.33 |
| 13 | $256.00 | $19.69 |
| 14 | $268.00 | $19.14 |
| 15 | $280.00 | $18.67 |
| 16 | $292.00 | $18.25 |
| 17 | $304.00 | $17.88 |
| 18 | $316.00 | $17.56 |
| 19 | $328.00 | $17.26 |
After updating the price of the hub, it is actually 8, not 7. I was using the old standard price for the hub of $85 in my original calculation.