rebuilt the hydraulics on my 98 yamaha 130...the only special tool needed was to open the caps on the ram seals. you can buy the wrench head on amazon. The one I got was adjustable, it wasnt as easy as the ones literally specifically made for opening your particular model of motor but so what it still worked.
I was able to find the full set of whatever seals I felt like replacing on boats.net. You shouldnt need to replace the entire assembly thats insane. It was literally no more than 10 rubber gaskets of various sizes and that was all.
You can search for parts by your engine part number. The job was really straight forward and youtube helps a ton. Open up the rams, Suck out/absorb as much of the old fluid as you can.
pull the rams, replace the seals on them with new ones, put them back in and close it up, then follow some of the youtube videos on how to refill your boats hydraulic fluid. Shops literally use synthetic power steering fluid that you can buy at canadian tire. Also very straight forward, my trick because i was doing it from empty was to blip the trim to pump fluid a bit to get some pressure built up as i went through the process of filling the reservoir again. Replacing the actual trim motor was really easy, 5 bolts and unplug it...plug it back in and put the bolts back in. I got my new motor, it was clearly 3d printed by a shop in Michigan, its pretty much just an electric coil, nothing fancy about that at all.
If you are mechanically inclined at all you can do the job yourself. If you really are hopeless, someone would do it for you for less than 3 grand, heck ill do it for you for a heck of a lot less than that as long as you can get the parts. Someone has to be making those rubber seals still, they dont need to be made by bombardier/BRP thats for sure.
Replacing the entire trim assembly because you have a few bad seal would be like putting a new axle, transmission and differential in your car because you need new tires lol
Post your Exact engine model number (it will be on the outboard) and I will search to find what you need for you.