There's someone who'd sell me an old lacie 4big raid for 60$. I think it looks kinda cool and would be handy to connect 4HDDs to my small computer - are there any doubts from such an "old" raid? I would be using new disks ofc. The thing came out in 2009 and has USB 3.0 and esata
If the drives are good, maybe. If not, you are looking at buying 4 drives from their compatibility list.
Do you already have a storage server? I'm running TrueNAS on a computer I retired a few years ago. I have 4 1TB drives in it and am about to install a used SAS card I got from eBay for $40 to add up to 6 more. It should give me 8tb of space.
I have seen more (client-owned) La Cie drives fail than I can remember. I wouldn't touch their crap with a 10 foot cable. Their on-board hardware controllers are the worst, cheapest garbage I've encountered on the "name brand" market.