Orschlens,
TSC or Rural King would all have what you need. I get much of my stuff from Orschlens.
Our store stocked a 12 volt fence charger from Zareba, rated for something like 10 miles of fence (might have been 0.6 joules). Cost was around $90. Hook the power leads of that up to a 12 volt deep cycle car battery (Orschelns' would have those as well....group 24 size cost about $70). You will then need a battery charger, which runs about $30.
View attachment 1457550
On this setup, the ground rod for the fencer is simply the steel post, which is doubling as a corner post. Fencer could also have been hung on the same steel post. Drive the post at least a foot into the ground and it should work.
One roll of the white poly tape or rope.....those may come in rolls of 660 feet or 1320 feet (1,320' = 1/4 mile). It will pay to go to the premium stuff, which has more wire, which ups the chance of the animal touching it, and also lowers the resistance level of the poly rope, meaning it is less work for the charger and gives a better shock.
The white step in posts also came from Orschlens. Their store brand posts are ok, but there is a better version from Parmak.......
https://parmakusa.com/product/bigfoot-step-in-post/
They might also be sold under the name "Bayguard", which is a Parmak brand. They seem heavier and more durable to me, but any of them will work. Cost of those runs about $3 each and on level ground, you can space those about 20 feet apart.....so that gives you some idea on how many you might need.
If you have uneven ground, likes dips or valleys, you can get the wire to hug the contour by using the yellow clip on insulators that are used on T posts, and install them upside down, to hold the wire/tape/poly rope down vs holding them up. Set the T post in the bottom of the trough and a white step in post on the shoulder or bank on either side.