Sadly thats not a good strategy anymore. Some domain registrars will take ownership of an expired domain and then try to sell it themselves for more. And even if the domain registrar isn't being evil, other people/companies monitor what expires and will snatch them up to resell, figuring it's worth something. Enough people buy domains at higher prices to make it profitable.

About a year ago, I stopped trying to grab a domain I've wanted since 1999. At one point I even had a "buy this domain if it expires" watcher active somewhere, and it still was snagged somehow. Just add "buy the domains I want" to the "If I gain the ability to time travel" wishlist