A PHD has 4 parts, boom, PTO shaft, gearbox & augur. All cost around $200 each new & are commodity pieces that are readily available even if the OEM for your PHD is unknown or gone.
If the PTO shaft has been greased & the gearbox kept properly filled (about half way) with oil, they realistically won't wear out with non-commercial use. The only part that will wear is the digging teeth on the augur. Those cost about $20-40 and are wear items that should be expected to need replacing every so often. Any tractor implement will end up rusty & ugly shortly, so that doesn't matter much.
I regularly see PHDs go at auctions for over $500, which is pretty much the price of a new County Line one. So either the slightly beefier ones that are pretty ugly are worth equal to a new cheaper one from the farm store or people are stupid & blowing money at auctions. I find either explanation equally plausible.
I suspect that a cheap County Line PHD will be good for most occasional users.
I'd check to see if it fits or drags on somewhat level ground & go for it if you can get it for cheaper than a County Line one. Yes or no is a toss up.