Shimano M520's are what I started out with. I realize they're not clipless/platform like you stated, but... I do XC / AM and have no problems with 'em. They have a screw on them that allows you to control tension. Great for newbies to clipless. They're durable too - I've never had any problems with them.

50$ for a set off of price point. I think I paid 60$ at the shop for 'em.

http://www.pricepoint.com/detail/164...SPD-Pedals.htm