Ka Band equipment and service Cost

YAHSAT:

GlobalTT might know. They are offering Ka space segment capacity. Not sure about Ka band equipment.
See https://www.globaltt.com/en/coverage_yahsat.html

O3B:

A completely different approach using a constellation of medium height orbit satellites is planned by O3b with their first batch of satellites due for launch 24 June 2013.
This system offers very high bit rates but requires teleport stations with dual tracking antennas for 24hr continuous service.
read more: https://www.o3bnetworks.com/o3b-advantage/our-technology

I think the +/- 45 deg coverage shown needs 8 satellites for continuous coverage at the north south limits.
If you are within +/- 22 deg of the equator, then a minimum of 5 satellites is required.  4 satellites are due in the first batch to be launched.

Initially, I would expect one or two customer teleports per country, with a substantial local area network around each.

Shows dual 4.5m ViaSat antenna installation in Cook Islands (Pacific)

Best regards, Eric.

Consider also Ka band capacity on HYLAS 2

Much will depend on your location in East Africa.  You say you are wanting 20 - 40 Mbit/s.   If this is for internet access then you just need a beam over your area and an earth station at your site. A teleport hub somewhere, e.g. UK or Cyprus, can do the other end connection to the terrestrial network.   If you want a point-to-point link then you need to check with Avanti that capacity in the relevant beam to beam interconnectivity is possible and available in both directions. Typically any "up" beam may be connected to a "down" beam on a per transponder basis.  But, these permutations soon become assigned and used up.

If you want East Africa to East Africa beam connectivity, e.g. Kenya to Kenya, you still need to ask if such transponder connectivity is available.

Best regards, Eric.