Big C south Pattaya, there is a boot inside next to the cashiers, very good guy Khun Anek and service, installation (at the parking lot) included in the product - did mine 2 years ago....
FES on Sukhumvit right at entrance/exit motorway 7
https://www.google.co.th/maps/place/บริษัท+เฟิสท์+อีสเทิร์น+ซัพพลาย+จำกัด/@12.9452393,100.9044889,21z/data=!4m6!3m5!1s0x3102be1d769d2b37:0xc1dee9e333377ad5!8m2!3d12.9452382!4d100.9043506!16s%2Fg%2F1tgnp2_5?hl=en&entry=ttu
yes 800 THB about standard price for taxi this route, Bolt should be 400-600 but not always available ex UTP, but if you gamble could be ok
AFAIK no bus/minibus service available