Wildthing covered it pretty well. There are much cheaper ways than using an entire Gallagher system. I went with all Gallagher because I was unexperienced with E fence and I thought I'd get the best guidance and customer support than if I built my own.
The basic Gallagher solar charger is almost $300. If I had it to do over again, I'd go with the Parmak.
If you really want to save money, go with a direct (AC) wire charger instead of a solar (DC) unit, but direct wire isn't usually an option for most plotters because plots are seldom near a power source.
The next overly expensive Gallagher component is the 1" posts. They are stout and convenient but there are much cheaper alternatives. Their step-in posts aren't too expensive...about $2.49 each. The heavy 1" posts are twice that much. IMO, other than the corners, you don't need a lot of strength in the posts. You just need them to hold the tape and wires up off the ground for the most part. The corners do get a fair amount of side stress so strong corners are best. I rotate my fence to other plots so I haven't done permanent corners.
IMO, fence tighteners are not needed. You can easily adjust taughtness by wrapping the strand around an insulator.
Ground rods...1 single, 3 foot rod, in a 1 acre fence system, has work fine for me. But the type of soil and soil moisture has a lot to do with how well a ground rod does it's job. I guess someone with sandy, droughty soil will need more grounding than what I need.
Testers are nice, but an old farmer showed me the poor man's way to check fences. Just take a blade of green grass and touch the fence with it. You'll feel a very much reduced "shock"...more like a sensation than a shock. But there are chargers out there that are scary powerful and I've never tried the grass trick with a high powered fence.
I fully agree that there's a learning curve to installing/removing a fence. Storage reels are an absolute must. Don't try to just coil the wire/tape. Believe me...you'll be sorry the next spring...that is a fact! Reels will really speed-up the entire process, too. You won't need reels to put up new fences up the very first time, but after that, you will want a reel for removing/installing each strand.
And I always take my fence down when I want to allow the critters in. I don't just turn it off. I want deer to always fear the fence when they see it. I never allow my fence to be uncharged while it's in place, so taking it down is a yearly chore. Using reels and developing a system makes a huge difference in the amount of time and frustration level you will experience.
I love my fence. I can develop a mature plot of sunflowers, or beans, or cowpeas. The kind of stuff that deer will destroy as it sprouts if I didn't have a fence.
Now, if the fricken rain would stop for just one day, I could get out there and prep my sunflower plot. BTW, wives love sunflower plots...makes it a lot easier to get them to accept the cost of a fence.