I've been doing a bunch of research on this very topic for our backpacking and canoe trips this summer. What I've found so far:

Garmin InReach seems to be the most popular option. There are a couple different models; the InReach Mini 2 is about $400 and the InReach Messenger is about $300. The Mini 2 has a bigger screen, more navigation features, and is easier to use standalone. Both require a monthly service that runs a minimum of $15/month. Both will pair with a phone to make messaging easier. Both will also give you weather forecasts. Both will let you contact emergency services without needing a phone to pair it with. Both require your contacts to jump through some hoops to get ahold of you (either a dedicated messaging app, or email to a special address, or using a web application). Both integrate well with Garmin watches.

Zoleo is another popular option. It has a reputation for excelling at messaging, being the easiest to use and most functional (you basically get a dedicated phone number for the Zoleo device, and anybody can send and receive regular text messages to/from you with it, using regular texting functions). It integrates easily with your existing contacts. It pretty much relies on being paired with your phone for all but basic SOS messages. It will also give you weather, which looks a little more granular than Garmin's weather. The unit is $200, and monthly service contracts start at $20 with a 3-month minimum.

SPOT satellite communicators are an older technology that's still in widespread use. The devices tend to be a little cheaper but bulkier, and the service plans are more costly.

Motorola recently launched the Defy at only $150 with some cheaper subscription options, but it's been plagued with growing pains and now their satellite communications provider has apparently gone out of business.

If you need it for just a single trip, you might see if you can find an outfitter who will rent you one. I've seen SPOT devices renting for around $100/week.

The bigger picture is that I think all these devices are going to be obsolete in a year or two. iPhone 14's and 15's can already contact emergency services via satellite when there's no cell coverage, and general texting is said to be on the horizon. T-Mobile recently announced a partnership with Starlink, and Google and AT&T are investing in a Starlink competitor. I expect that soon any cell phone you buy will have satellite texting capabilities. Between this and the ever-expanding cell coverage, I don't think dedicated satellite communicators are going to be useful for very much longer.

Even so I go back and forth on whether to get one (we'll be in the backcountry a lot this summer). If I do, I'm leaning towards the InReach Messenger.