Sounds about right if you get a shop to do it. But really depends on what features you want/need (as J0nx mentioned)
A good place to start: crutchfield (.com or .ca) and run through the "what fits my vehicle" which will tell you what size speakers you need. They also include adapter mounts, instructions, harnesses to make your life really easy. You can narrow down what you need/want from there and then do some price shopping
I'd start by looking at a deck that suits your needs (ie BT, usb, video, gps ... etc) and see what wiring harness you'll need (ask an you shall receive). Get that installed and then move up to replacing speakers.
There are tons of guides and walkthroughs to do this yourself. I installed a complete package: deck, amps, sub, 4 speakers, 2 tweeters, crossovers, BT, ... All with very little experience. Just had to match up similar color wires and solder them together.
Budget out what you want and post it. You'll get opinions from the WF.