Skeeter is dead on

Stay in the 8X range for all the reasons he lists. I chose 8X in for my Pentax DCF-SPs and remain delighted with them. I won't go hunting without them.

The advantages of 8X over 10X include:

Brighter
Less noticable hand shake
Higher quality overall image in the lower price bionos
Wider field of view


Recommendation in your price range: Vortex Diamondback 8X42. Bought a pair for my son last year and they are truly unbelievable at that price point.