I believe plain copper (presumably non-insulated) will be a non-optimal choice - particularly because it will stretch. Plus, since it is coming from a spool it is very easy to kink it which can cause it to break - constant worry.
In the old days we would use the Alaska Way to take care of the stretching problem by hard-drawing it: We'd take plain copper wire and tie it off to the bumper of a truck, with an intentional kink in it right before the bumper. Then we would slowly drive forward to stretch it until it broke at the kink.
You would be amazed how far it would stretch until it was strong enough to break at the kink. During the process it is important to watch out for unintentional kinks, of course.
But that was then and this is now.
Now I use Hard-drawn 7-strand 14 Gauge Copper antenna wire.
(This is a listing for 200 feet on a spool for $32.99 + shipping.)
I bought two spools recently and it is great stuff.
(This example photo shows 50 feet from an eBay listing)
And of course, an antenna is not simply made of a piece of wire. To make the total skyhook you'll want to mount it.
I also use small egg insulators at the end of the wire, with the antenna wire folded back and secured with a small hose clamp:
To string it up I use 3mm Mastrant-P for a particular run where it is used for tensioning - can't have the long 80-meter wires drooping down over the yard
I'm building a multi-band fan-shaped dipole that will be up for years to come, so decided the price was worth it.
Dipole antennas: Will paracord hold up well enough in the sun? Is there a better alternative?
Paracord works but stretches more. So it is fine for shorter runs and a lot more affordable.
This is Mil-Spec 7-strand Type III Nylon at a very affordable price
You can decide whether the wallet trumps quality.