That’s about exactly what I had done as well- it was about 2 years ago, but right around $800-900 bucks and a Bradford White 50 gal gas water heater, replacing a 17 year old Bradford White 40 gal gas heater.
800 isn’t a bad deal at all for a gas heater; $500 of that is the heater itself, and I’d guess you probably have another $50-100 or so in water and gas hoses/pipes/fittings/cut-off valves, and $200-250 in labor to haul the old one off, bring the new one in, install it, and make sure everything works.