As Mandy says, a good breeder should. worm them for you before you get them. Personally, I worm weaners with Panacur pellets, mixed in with the feed, and I also give the buyer another dose for each piglet to take home with them, just in case. This is because the downside with pelleted wormer is that you can't know for sure that each piglet has had the right amount.
However, as all my sows are vaccinated for internal and external parasites before farrowing, their piglets get some immunity, too.
If your weaners are wormed before you get them, you shouldn't have to do them again if you are only raising them for meat. If, later on, you decide to get into breeding, you should consider vaccinating your breeding stock with something like Dectomax (which I use) or Ivomec or something similar.
Hope this helps. Glad to see you've enjoyed keeping pigs so much that you're taking on a second batch!