How much do you want to spend & how bad are they?
Cheapest option is a good wire brush (mind the tyres though!) & "Smoothrite" or "Hammerite" dependant on the finish you want. It's not cheap paint & you can only put on one coat (a second within 6 weeks or so will make the paint bubble & do weird things) but it does look good & will last if done well, kills future build up of rust too.
I would think that the expense of removing the wheels & tyres then sandblasting & spraying wouldn't be worth it, you could probably pick up a set of better wheels on the cheap if you look around. Try good ol' ebay, I've found some reet Landy bargains already.
Cheers,
Marcus.