I just bought new boat and was wondering about a live scope unit. What do I need to buy to get one. Looks like there are several pieces to it and not a 1 box with all. I am used to hummingbird fish finder with a display unit and transducer. Thanks for any info you can give on this.

Hummingbird is a little behind, so unless you want to wait a while for them to ketchup to Garmin and Lowrance your going to need to switch brands.
You can get you a Garmin 10" without the mapping feature to save you on cost, then you will need the black box and the transducer all in a bundle for around 3k plus install
If you get the maping feature your looking at $3,500 plus install
If you use your Hummingbird for your mapping you then just don't need the Garmin Mapping extra cost as your just going to use it for forward facing sonar

I did the three part Garmin for about $2500 with a 10 inch screen. Around $200 for separate pole (crappie) and $200 for dedicated lithium battery (24 amp). I have no special skills and did the install in a rod box. Use a plug to plug adapter so you remove and replace battery for charging.

go to the garmin site and look at what is compatable and what retail price is then shop around. if you are good with the 32 instead of the newer version it is cheaper now.

I use a 9" echomap and it works fine for my type of fishing, crappie guys like the bigger screens and most bass guys use the big ones (I couldn't afford the bigger when I upgraded).

if you are good with a 9" the echomap touch screen runs around 1,000 retail and goes on sale often.

My boat came with HB mega live, I could see my crappie jig okay but I felt like livescope was better, I use my HB for SI, mapping, and way points since I already had it, once I go to a spot I've marked, I use livescope to see the fish, if you can afford it, get a 12'' screen on your garmin unit.

you need this:
https://www.garmin.com/en-US/p/806410
&
Then you need to pic the size graph you're wanting, something like this:

https://www.garmin.com/en-US/p/626316

Just for your info the Echomaps are not compatible with the new LVS 34 transducer. My transducer went out and I had to replace it with the 32.

to clarify though -
The LiveScope Plus transducer (LVS34) comes with a trolling motor mount, a shaft mount, and a perspective mode mount. LiveScope PLUS is ONLY compatible with GPSMAP® 8400, GPSMAP x2 Plus, GPSMAP x3, ECHOMAP™ Ultra, ECHOMAP UHD 7” and 9” series chartplotters..

You are correct my Echomap is a Plus touch screen and some of the Updates do not work with it. I think Garmin should make all these Screens compatible.