Cost for extension pipe installation with clock valves

I beleave my main water pipe goes in my kitchen, behind my kitchen cabinets. I want to hire a plumber to make a joint of stop valve and an extension pipe back through the wall to garden ( standard pipe length 2 ~ 3 meters and 1 meter at the end is flexible pipe), and a same length pipe come back the inside kitchen through the wall, join a stop valve and connect to main supply water pipe to whole house water system. ( 2 heads of flexible pipe outside garden are used to connect to my pressure pump system, I can do it myself or ask the plumber). I wonder how much it cost for the work of joining extension pipes and stop valves? Maximum could be? Thank you very much in advance! Regards, Thu