You originally wanted only a Zone 1 dish installed in the other thread.
https://www.satellites.co.uk/forums/threads/installer-required-for-consett-area.165162/
Around here there are of course plenty of installers, but you get a lot of bad in with the good, pricing is going to be less important to a bad installer who knows you have a choice to go elsewhere, and the good will often have to come close to matching the lowest common denominator pricing.
Around where you are the rarity, and I assume the distances between jobs, will mean any good installer within the catchment area will have to cover his travel costs, and any risk of having to carry duplicate equipment (just in case what you have is not up to the job), and/or return to fix anything failing under warranty will charge a higher rate .
I believe £100 is very good value if this is in writing and includes everything but the pole and cable (plus from memory T +Ks, connectors, clips, cable ties, insulation/almalgamating tape, fuel, general van and tool wear, packed lunch etc).
Bite their hand off.