You can not get a price without telling what engine is. ERR is an easy thing to do. Most people can do it. DCS PS3 upgrades require a bit more work and knowledge. If you are going to have one done, I strongly suggest you go to an MTH certified tech. I have seen some very nasty work done by self proclaimed experts. Stay clear from those people.
One thing that I am a bug on. If you buy an upgrade kit and plan on having someone do the job, DO NOT OPEN THE KIT AND PLAY WITH THE BOARD. Give the kit to the tech with the box sealed. I had a man from another state travel to me with two PS1 Big Boys. I told him when he purchased the kits at York to not open them. He opened everything after being told not to do so. I sent him home with his engines and kits. Being a person who does these upgrades it is tough as you need to stand your ground.
From the start of the ERR posts I have had several calls to do upgrades. I have 191 DCS upgrades under my belt. I did the first PS3 Diesel for MTH about a year before the kits came out. Early on, the diesel was going to use the PS32 board and they changed it last minute to a PS3 Diesel board. I see many non tech guys get in trouble as they do not know about flashing the chain files.
Bottom line on labor, depends on the engine. I have been to many schools (Trains) and if I pick a job I am always fair but it gets done right. I do not do these to pay bills. I have other work I do and usually tell people to call George.
Years ago when Mike changed his mind on doing upgrades due to popular demand, nobody could see the future and realize many other brands would be upgraded by the kit. I have done Lionel, Weaver, K-Line, 3rd Rail, and Williams. The kit can go a long way only limited to your fabricating skills. Doing upgrades has let me build up a big stock pile of PS1 and other boards. For a good length of time I had a guy who would buy several PS-1 board sets to upgrade his Williams engines. I have another guy in Mid America who does lots of upgrade work but does not know the computer. He sends me boards and I install the files he needs. A win win for both sides.
Pay whatever a tech wants and you should be alright.