One LDS charges $40 for hydro, VIP, and fill. They will replace some valve o-rings for free as part of the service, but a complete valve overhaul is an additional $65.
I've overhauled all my valves myself and am taking a bunch of cylinders and some fire extinguishers to a large regional hydro test facility later this week. They charge $19 for hydro and another $1 for a VIP sticker at the time of hydro, and visual eddy (for the "bad" 6351 alloy) is another $5. These prices do not include a high-pressure fill, they just pressurize with enough dry air to prevent corrosion. I've talked with them on the phone about my cocktail mix of problem cylinders which include one with the 6351 alloy, two that will require internal shot blasting, and one pair each made under the Worthington and PST special permits -- and they've been very accommodating. They mostly work with commercial, industrial, and medical clients that hydro hundreds of cylinders every year, but seem happy to accept over the counter work.
I've been buying used cylinders lately and have seven cylinders that are out of hydro plus one that will expire next year, along with a half a dozen fire extinguishers that are out of hydro. It's worth the trip.
I gather that the situation varies regionally with some areas having LDS prices that are extremely reasonable.