Used suspension bits. Bad idea?

[Lil'RedGTO]

Picked up some used Monaro suspension front struts and rear shocks and springs cheaply on a certain online auction site the other day. Seller (who isn't on here) claims they came off a facelift CV8 with only 3000 miles, so in theory they should have more life in them than those currently on my car (which has done 64,000 miles). Assuming he is telling the truth (big assumption I know, but I spoke to him and he seemed genuine) it seems like a no brainer to swap these in, as they must surely be in better condition than mine. Are there any downsides or risks to fitting used struts like these? Will it matter if they have been sitting off a car for a while? Is there any way to test them somehow before fitting them to the car?

[KMud]

If they seem tidy (they look quite good in the photo, suspension bits quickly look like hell) and you're doing the work yourself, toss 'em on I say. ~£600 worth of bits new isn't it?

[Yanayaya]

It's a tough one, personally I wouldn't but that's my own preference. There are certain areas I don't look to save money and those tend to be brakes, suspension and tyres.