Good lined shift housing is about $1 a foot for materials, with one foot required for the rear loop on a bike with down-tube shifters. Even running Campagnolo branded housing bought 660mm at a time you'd use $5 worth. Generic cables can be found for $1 although expensive ones run $5. They'd probably want to do the brakes and front derailleur at the same time, although things don't wear out at the same rates. You may also be getting a fixed price which applies to newer bikes with brake/shift levers that have more housing routed under the bar tape.

I strongly suggest doing your own work. Apart from wheel building I can't think of anything which is more work than driving to a bike shop, especially if you need to make a return visit for pickup.

Usually the tools needed for a job which last a lifetime are priced similarly to one-time service at the bike shop with a nice repair stand being the one notable exception.

I'd go with un-lined housing because with just 5-8 cogs and down-tube shifters you really don't need lower friction to begin with, and it'll last a really long time. I changed mine once in 15 years.