10 days in North Vietnam - drivers/guides?

My husband and I are spending a couple of weeks in North Vietnam, during which we want to spend 10 days travelling through Cao Bang, Ba Be, Ha Giang and Sapa via private car. Ideally we want to be picked up from Tuan Chau marina and then:

Day 1: drive from Tuan Chau to Cao Bang, check in at hotel

Days 2-3: day excursions from hotel

Day 4: drive to Ba Be, check in at hotel

Day 5: day excursion from hotel

Day 6: drive to Ha Giang

Days 7-8: drive around Ha Giang Loop, different hotels each night

Day 9: drive to Sapa, night market, overnight in Sapa

Day 10: excursions around Sapa, travel to Yen Bai in evening to stop halfway to Hanoi

Day 11: finish the journey by continuing from Yen Bai to Hanoi

We're arranging our own accommodation and meals so all we need is transport and a bit of guiding. But even without accommodation etc, a tour company quoted us over $2700 for this trip! This seems crazy - we were expecting something more in the region of $800-1000. We hired a driver in Kerala for a fairly similar itinerary for about $400 a few years ago so we were quite shocked at the difference.

So we're looking at using separate operators throughout now, or trying to find a different company. Does anyone have any tips about private drivers who might be able to take us throughout the whole trip, or separate drivers/companies to take us between/around each destination? Any other advice on what we should expect cost-wise/how to avoid being ripped off?