If you get one of the auto-darkening helmets from Harbor Freight be sure to check how fast it darkens and if it meets ANSI standards. Get one of the ones that does meet the standards and darkens in 1/20,000th of a second or less. This will protect your eyes as well as any of the $200 helmets, and Harbor Freight has them for as little as $50-$60 on sale.
Note that while the Harbor Freight helmets will protect your eyes, there is no denying that they are cheap helmets. They are made rather flimsy and are definitely not something I would recommend for anyone who really does a lot of welding. For the occasional hobby-welder they are fine. For anyone who plans on doing some welding almost every weekend I would recommend something more sturdy.