Where can I buy TV series box sets on DVD?

What genre are you interested in? That way I can better understand what kind of box set you're looking for.

Anyway, the usual places to find them are Amazon, eBay, and generic online sales sites. Amazon usually has a good selection and fast shipping, eBay might be worth it if you're looking for rare or out-of-print stuff because there are private sellers selling collections. Then there are local comic and DVD shops, if you have a decent one in your area it's worth stopping by because sometimes they have stock you won't find online, and the staff can give you recommendations.

If you want to save money also check out MediaWorld, Unieuro, and similar shops, sometimes they have decent discounts on box sets. Another option is buying used from people selling on Facebook Marketplace or Subito.it, it really depends on how much you're willing to spend and whether you care about having it in perfect condition or if a more worn copy is fine with you.

if you're looking for dvd box sets, i gotta be honest, it's not easy to find them everywhere anymore because the market has really shifted toward streaming 😅 amazon and ebay are still your main options though i'd also add checking the websites of italian publishers directly (like eagle pictures, koch media etc) because they often have outlet sections with decent discounts on old stock. then if there's still a physical media shop in your area, it's worth asking them directly - sometimes they have stuff you won't find online and maybe they'll even give you a better price

Try secondhand online shops like Vinted or Subito too - you can sometimes find entire series at much lower prices since they're sold by private sellers. Amazon and eBay remain the most complete options, but there's one detail a lot of people don't think about: check carefully whether it's the Italian edition or original language with subtitles, because prices vary quite a bit and it's not always clear from the listing.

Then think about whether you actually want the physical copy: a lot of series nowadays only come out on streaming and the DVD box set is really hard to find, or it costs triple the usual price. If the series you're looking for is relatively recent, it's probably more convenient (and less frustrating) to go with an online platform rather than hunt for boxes that might not exist anymore.