One thing to keep in mind - if your boards were planed before you
bought them, and if it was the planer that left the marks, you might
not end up all that much better if you get a cheap planer and re-plane
them yourself. Is there a real tool dealer in your area (HD or Lowes
don't count)? I'd also reconsider the use of a hand plane - I've been
using one along with a card scraper to get rid of machining marks, and
I've found that combination to be very effective, much quicker than
sandpaper or a ROS, and even sort of fun. (Watching beautiful grain
appear from rough-cut boards is really amazing...) Same quality thing
applies, though - unless you want to spend a bunch of time tuning a
hand plane, plan on spending about $150 on something nice from Steve
Knight or Lee Valley.
I don't discriminate against "tailed" tools, though - I've been using
my router table as a jointer to smooth the edges of boards, and found
that to be quick and easy also.